Glassory Backup
Contents
• 1 Bipolar Junction Transistor (BJT)
• 2 Capacitance Meter
• 3 Capacitor
• 4 Controlled Limiter Block
• 5 Controlled Sine Wave Oscillator
• 6 Controlled Sources
• 7 Controlled Square Wave Oscillator
• 8 Controlled Triangle Wave Oscillator
• 9 Current and Voltage Sources
• 10 Current-Controlled Switch
• 11 Differentiator Block
• 12 Diode
• 13 Divider Block
• 14 Frequency Meter
• 15 Gain Block
• 16 Ground
• 17 Hysteresis Block
• 18 Inductance Meter
• 19 Inductive Coupling
• 20 Inductor
• 21 Integrator Block
• 22 Junction Field Effect Transistor (JFET)
• 23 Limiter Block
• 24 Linear Current-Controlled Current Source (CCCS)
• 25 Linear Current-Controlled Voltage Source (CCVS)
• 26 Linear Voltage-Controlled Current Source (VCCS)
• 27 Linear Voltage-Controlled Voltage Source (VCVS)
• 28 Lossless Transmission Line
• 29 Lossy Transmission Line
• 30 Magnetic Core
• 31 Marker
• 32 MESFET
• 33 MOSFET
• 34 Multiplier Block
• 35 Mutual Inductor
• 36 Nonlinear Dependent Sources
• 37 Nonlinear Resistor, Conductor, Capacitor, and Inductor
• 38 Operational Amplifier (Op Amp)
• 39 Piecewise Linear (PWL) Controlled Source
• 40 Resistor
• 41 S-Domain Transfer Function Block
• 42 Summer Block
• 43 Thermometer
• 44 Transmission lines
• 45 Uniform RC Transmission Line
• 46 Voltage-Controlled Switch
• 47 XSpice Devices and their models
• 48 Zener Diode
The BJT is an active device which has up to 4 pins. The three standard pins are base, emitter, and
collector. These are given in the default symbol. The substrate, which is grounded by default, is the
fourth pin. To use the BJT with the substrate, create a new 4-pin BJT using the Device Editor and
Symbol Editor.
The standard device parameters are AREA, OFF, IC, and T. They are described below:
AREA area factor (optional) (If not specified, the default value is 1.0.)
OFF initial condition for the DC analysis (optional)
initial condition (optional) (Used when a transient analysis is desired, which starts from other
IC
than the quiescent operating point.)
T
operating temperature of the device (optional)
Area factor scales the model parameters RE and RC. IC VBE is the initial voltage from base emitter.
IC VCE is the initial voltage from collector to emitter. TEMP is the overriding temperature. These
parameters are based on the Gummel and Poon integral-charge model. If these parameters are not
specified, then it will reduce to the simpler Ebers-Moll model.
The process model is mandatory for the BJT. Descriptions of the process model parameters are
given in the following table:
NAME
IS
BF
NF
VAF
IKF
ISE
NE
BR
NR
VAR
IKR
ISC
NC
RB
IRB
RBM
RE
RC
CJE
VJE
MJE
TF
XTF
PARAMETER
transport saturation current
ideal maximum forward beta
forward current emission coefficient
forward Early voltage
corner forward beta high current roll-off
B-E leakage saturation current
B-E leakage emission coefficient
ideal maximum reverse beta
reverse current emission coefficient
reverse Early voltage
corner reverse beta high current roll-off
B-C leakage saturation current
B-C leakage emission coefficient
zero bias base resistance
current where base resistance falls halfway to minimum value
minimum base resistance at high currents
emitter resistance
collector resistance
B-E zero bias depletion capacitance
B-E built-in potential
B-E junction exponential factor
ideal forward transit time
coefficient for bias dependence of TF
UNITS DEFAULT EXAMPLE
A
1.0e-16
1.0e-15
100
100
1.0
1
V
infinite
200
A
infinite
0.01
A
0
1.0e-13
1.5
2
1
0.1
1
1
V
infinite
200
A
infinite
0.01
A
0
1.0e-13
2
1.5
ohms 0
100
A
infinite
0.1
ohms RB
10
ohms 0
1
ohms 0
10
F
0
2pF
V
0.75
0.6
0.33
0.33
sec
0
0.1ns
0
VTF
ITF
PTF
CJC
VJC
MJC
voltage describing VBC dependence of TF
high-current parameter for effect on TF
excess phase at freq=1.0/(TF*2PI)Hz
B-C zero bias depletion capacitance
B-C built-in potential
B-C junction exponential factor
of B-C depletion capacitance connected to internal
XCJC fraction
base node
TR
ideal reverse transit time
CJS zero bias collector-substrate capacitance
VJS substrate junction built-in potential
MJS substrate junction exponential factor
XTB forward and reverse beta temp. exponent
EG
energy gap for temperature effect on IS
XTI
temperature exponent for effect on IS
KF
flicker-noise coefficient
AF
flicker-noise exponent
FC
coefficient for forward bias depletion capacitance formula
TNOM parameter measurement temperature
V
A
degree
F
V
infinite
0
0
0
0.75
0.33
2pF
0.5
0.5
1
sec
F
V
0
0
0.75
0
0
eV
1.11
3
0
1
0.5
deg. C 27
10ns
2pF
0.5
50
The Capacitance Meter measures the total capacitance between a circuit node and the ground. The
input pin of the device is connected to the measurement node. The output voltage of the device is
then a scaled value equal to the total capacitance seen on its input multiplied by the gain parameter.
This model is primarily intended as a building block for other models which must sense a capacitance
value and alter their behavior based upon it.
Model Identifier: cmeter
Netlist Format:
A<device_name> <in_pin> <out_pin> <model_name>
.model <model_name> cmeter {<gain = value>}
Example:
A1 1 2 cap_meter
.model cap_meter cmeter gain = 1
Parameters:
The only parameter is the gain with a default value of 1.0.
Capacitors are used to store electrical energy. They can filter or remove AC signals or block DC
current without disrupting AC signals. A capacitor's ability to store energy is termed capacitance and
is measured in Farads, with values from pF to mF. The only time current flows through a capacitor is
when the charge is collected on, or is removed from, its parallel plates. This means that the voltage
across the capacitor is changing, which doesn't conform to DC analysis. In a physical circuit, there is
a transition stage during which capacitors charge up to their final values. The result is the same as if
these capacitors did not exist and the connections to them were left dangling. In other words, in a
(steady-state) DC analysis, a capacitor behaves like an open circuit. Therefore, it is important that no
section of the circuit is isolated from the capacitors. Every circuit node needs some path for DC
current to the ground.
A capacitor's transient behavior is described by the equation:
i(t) = C * (dv(t)/dt)
Its initial voltage is only important when the simulator performs a transient analysis, and the "Use
Initial Conditions" checkbox is checked.
An capacitor's AC behavior is described by the equation:
i=j?*C*v
All capacitor names must begin with C.
Netlist Format:
C<device_name> <N+> <N-> <value>
Example:
C1 1 2 10p
B2.Spice A/D provides two types of capacitors: simple and semiconductor.
Simple Capacitor
The standard capacitor parameters are N+, N-, VALUE, and IC. In a simple capacitor, VALUE must
be specified and it is the capacitance in Farads. IC is the initial condition (optional) for the capacitor
voltage.
Semiconducting Capacitor
This allows for the calculation of capacitance from geometric information and the specifications of the
process in the model specification of the capacitor. If width isn't specificied, then the default width
given in the model is used. The optional initial condition ic is the initial voltage across the capacitor for
transient simulations.
The model parameters are as follows: CJ, junction bottom capacitance; CJSW, junction sidewall
capacitance; DEFW, default device width; NARROW, narrowing due to side etching, and CAP,
nominal capacitance for monte carlo. The capacitance is computed as:
CAP = CJ * (LENGTH - NARROW) * (WIDTH - NARROW)+ 2 * CJSW * (LENGTH + WIDTH 2NARROW) * CAP
To modify the model parameters, first double click on the capacitor to edit its top-level model
parameters, then choose the button in the process model section to Edit from Table and this will
open a window in which you can edit CJ, CJSW, NARROW, DEFW, and CAP.
The Controlled Limiter is a single-input, single-output block similar to the Gain Block. However, the
output of the Controlled Limiter function is restricted to the range specified by the output lower and
upper limits. This model operates in DC, AC and Transient analysis modes. Note that the limit range
is the value below the Upper Limit Control input signal (CNTL_UPPER) and above the Lower Limit
Control input signal (CNTL_LOWER) at which smoothing of the output signal begins. A minimum
positive value of voltage difference must exist between the CNTL_UPPER and CNTL_LOWER inputs
at all times. The main difference between the Controlled Limiter Block and the Limiter Block is that the
former's limits are set by input control voltages, while the latter's limits are set as numerical
parameters.
Also note that the Controlled Limiter function examines the input values of CNTL_UPPER and
CNTL_LOWER to make sure that they are spaced far enough apart to guarantee the existence of a
linear range between them. The range is calculated as the difference between (cntl_upper upper_delta - limit_range) and (cntl_lower + lower_delta + limit_range) and must be greater than or
equal to zero. When the limit_range is specified as a fractional value, the limit_range used in the
above is taken as the calculated fraction of the difference between cntl_upper and cntl_lower. Still,
the potential exists for too great a limit_range value to be specified for proper operation, in which case
the model will return an error message.
Model Identifier: climit
Netlist Format:
A<device_name> <in_pin> <cntl_upper_pin> <cntl_lower_pin> <out_pin> <model_name>
.model <model_name> climit {<param1 = value> < param2 = value> ...}
Example:
A1 1 2 3 4 controlled_limit_block
.model controlled_limit_block climit in_offset = 0.0 gain = 1.0 upper_delta = 0.0 lower_delta = 0.0
Parameters:
Name
in_offset
gain
Description
input offset
gain
Default
0.0
1.0
upper_delta
lower_delta
limit_range
fraction
output upper delta
output lower delta
upper and lower sm. Range
smoothing %/abs switch
0.0
0.0
1.0e-6
False
This is a four-terminal function generator with a sinusoidal wave output, whose frequency is controlled
by an input voltage. The functional dependency of the output frequency on the input voltage is
piecewise linear and is defined as a two-dimensional table similar to a piecewise linear (PWL)
controlled source. In the "frequency vs. voltage" curve, the array "cntl_array" defines voltage values in
Volts and the array "freq_array" defines the corresponding frequencies in Hz. This function has
parameterizable values of low and high peak output voltage.
Model Identifier: sine
Netlist Form:
A<device_name> %vd(<cntl_in_pin> <cntl_in_ref_pin>) %vd(<out_pin> <out_ref_pin>)
<model_name>
.model <model_name> sine cntl_array = [<value1> <value2>] freq_array = [<value1> <value2>]
{<param1 = value> < param2 = value> ...}
Example:
A1 %vd(1 3) %vd(2 4) sine
.model sine sine cntl_array = [0 1] freq_array = [1 1000]
Parameters:
Name
Cntl_array
Freq_array
Out_low
Out_high
Description
control array
frequency array
output peak low value
output peak high value
Default Notes
[0 1]
required
[1 1000] required
-1.0
1.0
Circuits can contain linear dependent sources characterized by one of the following equations (where
g, e, f, and h are constants representing transconductance, voltage gain, current gain, and
transresistance, respectively):
i=gv
v=ev
i=fi
v=hi
For further information, refer to:
Linear Current Controlled Current Source (CCCS)
Linear Voltage Controlled Current Source (VCCS)
Linear Current Controlled Voltage Source (CCVS)
Linear Voltage Controlled Voltage Source (VCVS)
This is a four-terminal function generator with a square wave output, whose frequency is controlled by
an input voltage. The functional dependency of the output frequency on the input voltage is piecewise
linear and is defined as a two-dimensional table similar to a piecewise linear (PWL) controlled source.
In the "frequency vs. voltage" curve, the array "cntl_array" defines voltage values in Volts and the
array "freq_array" defines the corresponding frequencies in Hz.
Model Identifier: square
Netlist Format:
A<device_name> %vd(<cntl_in_pin> <cntl_in_ref_pin>) %vd(<out_pin> <out_ref_pin>)
<model_name>
.model <model_name> square cntl_array = [<value1> <value2>] freq_array = [<value1> <value2>]
{<param1 = value> < param2 = value> ...}
Example:
A1 %vd(1 3) %vd(2 4) square
.model square square cntl_array = [0 1] freq_array = [1 1000]
Parameters:
Name
Cntl_array
Freq_array
Out_low
Out_high
Duty_cycle
Rise_time
Fall_time
Description
control array
frequency array
output peak low value
output peak high value
Duty cycle
Output rise time
Output fall time
Default Notes
[0 1]
required
[0 1000] required
-1.0
1.0
0.5
1.0e-9
1.0e-9
This is a four-terminal function generator with a triangle wave output, whose frequency is controlled
by an input voltage. The functional dependency of the output frequency on the input voltage is
piecewise linear and is defined as a two-dimensional table similar to a piecewise linear (PWL)
controlled source. In the "frequency vs. voltage" curve, the array "cntl_array" defined voltage values in
Volts and the array "freq_array" defines the corresponding frequencies in Hz.
Model Identifier: triangle
Netlist Format:
A<device_name> %vd(<cntl_in_pin> <cntl_in_ref_pin>) %vd(<out_pin> <out_ref_pin>)
<model_name>
.model <model_name> tirangle cntl_array = [<value1> <value2>] freq_array = [<value1>
<value2>]{<param1 = value> < param2 = value> ...}
Example:
A1 %vd(1 4) %vd(2 3) triangle
.model triangle triangle cntl_array = [0 1] freq_array = [1 1000]
Parameters:
Name
Cntl_array
Freq_array
Out_low
Out_high
Rise_duty
Description
control array
frequency array
output peak low value
output peak high value
Rise time duty cycle
Default Notes
[0 1]
required
[0 1000] required
-1.0
1.0
0.5
Sources have a DC value, a transient behavior, an AC behavior, and distortion parameters.
The transient type, AC parameters, and distortion parameters are defined on the first tab of the
source's property dialog.
The DC value of a voltage source is its initial transient value. For a source with a sinusoidal transient
behavior, for example, the DC value will be equal to its transient offset voltage.
The AC parameters are magnitude and phase. These are used during the AC Frequency Sweep
analysis. The distortion parameters, two sets of magnitude and phase, are used during the distortion
analysis.
The transient expression can be a pulse, sinusoid, exponential, or piecewise linear. Each of these is
described after the current source.
Switches are devices that exhibit high resistance when open (OFF state) and low resistance when
closed (ON state). The switch model allows an almost ideal switch to be specified. With careful
selection of the on and off resistances, they can effectively represent zero and infinite resistances in
comparison to other circuit elements, while sustaining the model condition of a positive, finite value.
There are two versions of Current-Controlled Switch: two-terminal and four-terminal. For the
two-terminal device, you must specify the name of the controlling Ammeter or voltage source, as well
as the turn-on and turn-off currents in Amperes and on and off resistance values in Ohms. The
four-terminal device already provides nodes for a controlling ammeter, and you just specify the rest of
parameters. When the current through the switch or controlling device is greater or equal to the
turn-on current, the switch closes. When the current through the switch or controlling device is less
than or equal to the turn off current, the switch opens.
NAME
I_ON
I_OFF
RON
ROFF
PARAMETER
turn-on current
turn-off current
closed resistance
open resistance
UNITS
Amps
Amps
ohms
ohms
DEFAULT
0.0
0.0
1.0
1/GMIN
The Differentiator Block approximates the time derivative of an input signal by calculating the
incremental slope of that signal since the previous time point. Gain and output offset parameters are
also included to allow for tailoring of the required signal. Output upper and lower limits are also
included to prevent convergence erros resulting from excessively large output values. The
incremental value of output below the output_upper_limit and above the output_lower_limit at which
smoothing begins is specified via the limit_range parameter. In AC analysis, the value returned is
equal to the radian frequency of analysis multiplied by the gain.
Model Identifier: d_dt
Netlist Format:
A<device_name> <in_pin> <out_pin> <model_name>
.model <model_name> d_dt out_lower_limit = <value> out_upper_limit = <value> {<param1 = value>
< param2 = value> ...}
Example:
A1 1 2 differentiator
.model differentiator d_dt out_lower_limit = -1t out_upper_limit = 1t
Parameters:
Name
Description
Default Notes
gain
gain
1.0
out_offset
output offset
0.0
out_lower_limit output lower limit
-1t
required
out_upper_limit output upper limit
1t
required
limit_range
upper and lower limit smoothing range 1.0e-6
Diodes allow current flow only in one direction, following their symbol's arrow, and thus can be used
as simple solid state switches in AC circuits.
The standard device parameters are AREA, OFF, IC, and T. They are described below:
AREA area factor (optional) (If not specified, the default value is 1.0.)
OFF initial condition for the DC analysis (optional)
initial condition (optional) (Used when a transient analysis is desired, which starts from other
IC
than the quiescent operating point.)
T
operating temperature of the device (optional)
The process models can be either junction diodes or Schottky barrier diodes. Area factor scales the
model parameters IS, RS, CJO, and IBV. VD is the initial voltage, and TEMP is the overriding
temperature. Descriptions of the process model parameters are given in the following table:
Name
IS
RS
N
TT
CJO
VJ
M
Parameters
saturation current
ohmic resistance
emission coefficient
transit-time
zero-bias junction capacitance
junction potential
grading coefficient
Units
A
Ohm
seconds
F
V
-
EG
XTI
KF
AF
BV
IBV
TNOM
FC
activation energy
saturation current temp. exp.
flicker noise coefficient
flicker noise exponent
reverse breakdown voltage
current at breakdown voltage
parameter measurement temperature
coefficient for forward-bias depletion capacitance formula
eV
V
A
degrees C
-
The Divider Block has two inputs. Each of the numerator and denominator inputs is added to its
respective offset and then multiplied by its respective input gain (with default values of 1). Next, the
loaded numerator signal is divided by the loaded denominator signal. The result is multiplied by the
output gain and then added to the output offset. To avoid division by zero, the divider function sets
the denominator signal greater than zero through the lower limit parameter. This limit is approached
through a quadratic smoothing function, the domain of which may be specified as a fraction of the
lower limit value or as an absolute value. The divider function operates in DC, AC, and Transient
analysis modes. In AC analysis, however, it is important to remember that results are invalid unless
the denominator input is a DC voltage.
Model Identifier: divide
Netlist Format:
A<device_name> <num_pin> <den_pin> <out_pin> <model_name>
.model <model_name> divide {<param1 = value> < param2 = value> ...}
Example:
A1 1 2 3 divider_block
.model divider_block divide den_offset = 0.0 den_gain = 1.0
Parameters:
Name
num_offset
num_gain
den_offset
den_gain
den_lower_limit
den_domain
fraction
out_gain
out_offset
Description
numerator offset
numerator gain
denominator offset
denominator gain
denominator lower limit
denominator smoothing domain
smoothing fraction/absolute value switch
output gain
output offset
Default
0.0
1.0
0.0
1.0
1.0e-10
1.0e-10
False
1.0
0.0
The Frequency Meter is a four-pin shunt device that is connected in parallel with an AC source just
like a voltmeter and measures the operating frequency of the AC circuit. The input pins are connected
across the AC source. The voltage across the output pins is equal to the frequency of the source in
Hertz within a scale factor SF. Note that the Frequency Meter is designed to work with a single-tone
AC source of unit amplitude. If the amplitude of the source is not one, multiply the SF parameter by
the non-unit source amplitude value. The output voltage of the Frequency Meter can be used in
conjunction with linear or nonlinear dependent sources to model frequency-dependent quantities.
Model Identifier: fmeter
Parameters:
The only parameter is the scale factor SF with a default value of 1.0. Set SF = 1e-6 to read out the
frequency in MHz. Set SF = 1e-9 to read out the frequency in GHz. Set SF = 6.283185 (2*pi) to read
out the angular frequency ω in radian/s.
This model is a simple gain block with optional offsets on the input and the output. In_offset is added
to the input, the sum of which is then multiplied by the gain, and the output offset is added to produce
the final output. The gain block model will operate in DC, AC, and Transient analysis modes.
Model Identifier: gain
Netlist Format:
A<device_name> <in_pin> <out_pin> <model_name>
.model <model_name> gain {<param1 = value> < param2 = value> ...}
Example:
A1 1 2 gain_block
.model gain_block gain in_offset = 0.0 out_offset = 0.0
Parameters:
Name
in_offset
gain
out_offset
Description
input offset
gain
out_offset
Default
0.0
1.0
0.0
Ground has a voltage of zero (0) and is used as a reference to compute electrical values in the circuit.
All circuits must be grounded to be properly simulated. There is no limit on the number of grounds
you may use in a circuit. All components connected to ground are referenced to a common point and
treated as linked through ground.
The Hysteresis block is a simple buffer stage that provides hysteresis of the output with respect to the
input. The in_low and in_high parameter values. The output values are limited to out_lower_limit and
out_upper_limit. The value of \93hyst\94 is added to the in_low and in_high points in order to specify
the points at which the slope of the hysteresis function would normally change abruptly as the input
transitions from a low to a high value. Likewise, the value of \93hyst\94 is subtracted from the in_high
and in_low values in order to specify the points at which the slope of the hysteresis function would
normally change abruptly as the input transitions from a high to a low value. In fact, the slope of the
hysteresis function is never allowed to change abruptly but is smoothly varied whenever the
input_dowmain smoothing parameter is set greater than zero.
Model Identifier: hyst
Netlist Format:
A<device_name> <in_pin> <out_pin> <model_name>
.model <model_name> hyst {<param1 = value> < param2 = value> ...}
Example:
A1 1 2 hysteresis_block
.model hysteresis_block hyst in_low = 0.0 in_high = 1.0
Parameters:
Name
In_low
in_high
hyst
out_lower_limit
out_upper_limit
input_domain
fraction
Description
input low value
input high value
hysteresis
output lower limit
output upper limit
input smoothing domain
smoothing fraction/absolute value switch
Default
0.0
1.0
0.1
0.0
1.0
0.01
true
The Inductance Meter measures the total inductance between a circuit node and the ground. The
input pin of the device is connected to the measurement node. The output voltage of the device is
then a scaled value equal to the total inductance seen on its input multiplied by the gain parameter.
This model is primarily intended as a building block for other models which must sense an inductance
value and alter their behavior based upon it. Care must be exercised when connecting an Inductance
Meter to the inductors of a circuit. This is due to the fact that inductors are treated by SPICE as
current sources. This can cause a problem when an inductor is connected in series with a current
source, or in series with a voltmeter, or in series with another inductor.
Model Identifier: lmeter
Netlist Format:
A<device_name> <in_pin> <out_pin> <model_name>
.model <model_name> imeter {<gain = value>}
Example:
A1 1 2 inductance_meter
.model inductance_meter lmeter gain = 1
Parameters:
The only parameter is the gain with a default value of 1.0.
The Inductive Coupling transformer couples any two existing inductors. It doesn't have any nodes
because it doesn't actually represent inductors, only the coupling between them. This is useful if you
want to couple two inductors that are in different parts of the circuit, or if you want to couple more
than two inductors together, use more than one of these, with each one coupling a pair of inductors.
The standard parameters are Inductor1, Inductor2, and K. Inductor1 is the name of first inductor,
Inductor2 is the name of the second inductor, and K is the coefficient of coupling, 0 < K ≤ 1.
Inductors are used to store magnetic energy. An inductor's ability to counteract current changes
passing through it is called its inductance (L), which is measured in Henrys. In a (steady-state) DC
analysis, the inductor acts like a short circuit. It is indeed treated as a current source, which can be
problematic if an inductor is connected in series with a current source, or in series with a voltmeter, or
in series with another inductor. The resistor may be of negligible value or one that accounts for the
coil resistance of the inductor. In AC and transient analyses, the inductor develops a voltage across it
in response to the changing magnetic flux within its coil.
An inductor's transient behavior is described by the equation:
v(t) = L*(di(t)/dt)
The inductor's initial condition is optional. It is the initial value of the inductor current in Amperes that
flows from node N+ through the inductor to node N-. The only time that the initial current matters is
when the simulator performs a transient analysis, and the "Use Initial Conditions" checkbox is
checked.
An inductor's AC behavior is described by the equation:
v=jω*L*i
All inductor names must begin with L.
Netlist Format:
L<device_name> <N+> <N-> <value>
Example:
L1 1 2 10u
The Integrator Gain and input offset parameters are also included to allow for tailoring of the required
signa. Output upper and lower limits are also included to prevent convergence errors resulting from
excessively large output values. Note that these limits specify integrator behavior similar to that found
in an operational amplifier-based integration stage, in that once a limit is reached, additional storage
does not occur. Thus the input of a negative value to an integrator which is currently driving at the
out_upper_limit level will immediately cause a drop in the output, regardless of how long the
integrator was previously summing positive inputs. The incremental value of output below the
output_upper_limit and above the output_lower_limit at which smoothing begins is specified via the
limit_range parameter. In AC analysis, the value returned is equal to the gain divided by the radian
frequency of analysis.
Note that truncation error checking is included in the \93int\94 block. This should provide for a more
accurate simulation for the time integration function, since the model will inherently request smaller
time increments between simulation points if truncation errors would otherwise be excessive.
Model Identifier: int
Netlist Format:
A<device_name> <in_pin> <out_pin> <model_name>
.model <model_name> int out_lower_limit = <value> out_upper_limit = <value> {<param1 = value> <
param2 = value> ...}
Example:
A1 1 2 integrator_block
.model integrator_block int out_lower_limit = -1t out_upper_limit = 1t
Parameters:
Name
gain
in_offset
out_lower_limit
out_upper_limit
limit_range
out_ic
Description
gain
output offset
output lower limit
output upper limit
upper and lower limit smoothing range
output initial condition
Default Notes
1.0
0.0
-1t
required
1t
required
1.0e-6
0.0
The JFET is the simplest transistor device and has three pins: gate, drain and source. The JFET
defaults are based on the Shichman and Hodges FET model. This is a square-law device because of
the expression relating the drain current to the gate-to-source voltage: Idrain=*(VGS-Vthreshold)2. In
real JFETs, near the saturation point, the drain currents vary with the drain voltages. This can be
modeled by the following formula: Idrain=*(VGS-VTO)2*(1+*VDS), which yields an increasing drain
current for increasing values of VDS.
The gate-to-source and gate-to-drain junctions each have a nonlinear capacitor. The zero-bias
capacitance value is selected for each junction.
The standard device parameters are AREA, OFF, IC, and T. They are described below:
AREA area factor (optional) (If not specified, the default value is 1.0.)
OFF initial condition for the DC analysis (optional)
initial condition (optional) (Used when a transient analysis is desired, which starts from other
IC
than the quiescent operating point.)
T
operating temperature of the device (optional)
The process model parameters are listed in the following table:
NAME
VTO
BETA
LAMBDA
RD
RS
CGS
CGD
PB
IS
B
KF
AF
FC
TNOM
PARAMETER
threshold voltage
transconductance parameters
channel-length modulation parameter
drain ohmic resistance
source ohmic resistance
zero-bias G-S junction capacitance
zero-bias G-D junction capacitance
gate junction potential
gate junction saturation current
doping tail parameter
flicker-noise coefficient
flicker-noise exponent
coefficient for forward-bias depletion capacitance formula
parameter measurement temperature
UNITS
V
A/V2
1/V
ohms
ohms
F
F
V
A
DEFAULT
-2
1.0e-4
0
0
0
0
0
1
1.0e-14
1
0
1
0.5
deg. C 27
EXAMPLE
-2
1.0e-3
1.0e-4
100
100
5pF
1pF
0.6
1.0e-14
1.1
50
The Limiter is a single-input, single-output block similar to the Gain Block. However, the output of the
Limiter function is restricted to the range specified by the output lower and upper limits. This model
operates in DC, AC and Transient analysis modes. Note that the limit range is the value below the
UPPER LIMIT and above the LOWER LIMIT at which smoothing of the output signal begins. For this
model, then, the limit range represents the delta with respect to the output level at which smoothing
occurs. Thus, for an input gain of 2.0 and output limits of 1.0 and -1.0 volts, the output will begin to
smooth out at ?+/-0.9 volts, which occurs when the input value is at 0.4V.
Model Identifier: limit
Netlist Format:
A<device_name> <in_pin> <out_pin> <model_name>
.model <model_name> limit {<param1 = value> < param2 = value> ...}
Example:
A1 1 2 limit_block
.model limit_block limit in_offset = 0.0 gain = 1.0 out_lower_limit = -1t out_upper_limit = 1t
Parameters:
Name
in_offset
gain
out_lower_limit
out_upper_limit
limit_range
fraction
Description
input offset
gain
output lower limit
output upper limit
upper and lower smoothing range
smoothing fraction/absolute value switch
Default
0.0
1.0
0.0
1.0
1.0e-6
False
The CCCS is a current source whose current is directly proportional to the current across a controlling
Ammeter or a voltage source. There are two versions: two-terminal and four-terminal. For the
two-terminal device, you must specify the name of the controlling Ammeter or voltage source, as well
as the current gain, which has a default value of one. The four-terminal device already provides
nodes for a controlling ammeter, and you just specify the current gain.
Model Identifier: cccs
Netlist Format:
F<device_name> <N+> <N-> <controlling_device_name> <value>
Example:
F1 1 0 V1 1.0
The CCVS is a voltage source whose voltage is directly proportional to the current through a
controlling ammeter or a voltage source. There are two versions: two-terminal and four-terminal. For
the two-terminal device, you must specify the name of the controlling Ammeter or voltage source, as
well as the trans-resistance gain, which has a default value of one. The four-terminal device already
provides nodes for a controlling ammeter, and you just specify the trans-resistance gain.
Model Identifier: ccvs
Netlist Format:
H<device_name> <N+> <N-> <controlling_device_name> <value>
Example:
H1 1 0 V1 1.0
The VCCS is a current source whose current is directly proportional to the voltage across a
controlling voltmeter or the voltage between two circuit nodes. There are two versions: two-terminal
and four-terminal. For the two-terminal device, you must specify the name of the controlling voltmeter
or the two controlling nodes, as well as the trans-conductance gain, which has a default value of one.
The four-terminal device already provides nodes for a controlling voltmeter, and you just specify the
trans-conductance gain.
Model Identifier: vccs
Netlist Format:
G<device_name> <N+> <N-> <NC+> <NC-> <value>
Example:
G1 1 0 2 0 1.0
The VCVS is a voltage source whose voltage is directly proportional to the voltage across a
controlling voltmeter of the voltage between two circuit nodes. There are two versions: two-terminal
and four-terminal. For the two-terminal device, you must specify the name of the controlling voltmeter
or the two controlling nodes, as well as the voltage gain, which has a default value of one. The
four-terminal device already provides nodes for a controlling voltmeter, and you just specify the
voltage gain.
Model Identifier: vcvs
Netlist Format:
E<device_name> <N+> <N-> <NC+> <NC-> <value>
Example:
E1 1 0 2 0 1.0
The lossless transmission line device models only one propagating mode. Should all four nodes of
the actual circuit be distinct, two modes may be activated and this device would be insufficient. To
circumvent this potential problem, two transmission line devices are required.
Optional initial condition parameters are the voltage and current at each of the transmission line ports.
Due to implementation details, you may produce more accurate simulation with the lossy
transmission line device with zero loss.
The standard parameters are Z0, TD, F, NL, IC. They are described below:
Z0 characteristic impedance
TD transmission delay
F frequency
electrical length of the transmission line with respect to the wavelength in the line at
NL normalized
frequency F. (If F is specified, but NL is not, the default is 0.25.)
IC initial condition (Specifies the voltage and current at each of the transmission line ports.)
It is a two-port convolution model for single-conductor lines. MNAME is the process model name,
which includes a set of pre-specified options as described below.
The lossy transmission device models a uniform constant-parameter distributed line, with parameters
as described in the following chart:
NAME
R
L
C
LEN
LININTERP
QUADINTERP
MIXEDINTERP
COMPACTREL
COMPACTABS
NOCONTROL
STEPLIMIT
NOSTEPLIMIT
PARAMETER
UNITS DEFAULT EXAMPLE
resistance /length
Ohm /m 0.0
0.2
inductance/length
henrys/m 0.0
9.13e-9
capacitance/length
farads/m 0.0
3.65e-12
length of line
m
none
1.0
use linear interpolation
flag
not set
set
use quadratic interpolation
flag
not set
set
use linear when quadratic seems bad
flag
not set
set
special reltol for straight line checking
flag
RETOL
1.0e-3
special abstol for straight line checking
flag
ABSTOL 1.0e-9
don't do complex time control
flag
not set
set
always limit timestep to 0.8*(delay of line)
don't always limit timestep to 0.8*(delay of line) flag
not set
set
use Newton-Raphson method for timestep
TRUNCNR
flag
not set
set
calculation in LTRAtrunc
limit timestep to keep impulse-response
TRUNCDONTCUT don't
flag
not set
set
errors low
The RLC (uniform transmission line with series loss only), RC (uniform RC line), LC (lossless
transmission line), and RG (distributed series resistance and parallel conductance only) lines have
been implemented. The length (LEN) must be given. COMPACTREL and COMPACTABS control the
compaction of past history values used in convolution. Larger values for these lower accuracy but
improve speed. These are used with the TRYTOCOMPACT option.
This device is used as a building block to create a wide variety of inductive and magnetic circuit
models. It is almost always to be used in conjunction with the "lcouple" model to build up systems
which simulate the behavior of linear and nonlinear magnetic components. There are two
fundamental modes of operation for the core model. These are the "PWL" mode (which is the default
and most likely to be of use to you) and the "Hysteresis" mode.
PWL Mode (mode = 1)
In the PWL mode, the model takes a voltage as input which it treats as a magnetomotive force (mmf)
value. This value is divided by the total effective length of the core to produce a value for the
Magnetic Field Intensity, H, which is then used to find the corresponding Flux Density, B, using the
piecewise linear relationship described by you in the H_array / B_array coordinate pairs. B is then
multiplied by the cross-sectional area of the core to find the Flux value, which is output as a current.
The pertinent mathematical equations are:
H = mmf / L, where L = Length (in apmere-turns/meter)
B = f(H)
Φ = B * A, where A = Area
The B value is derived from a piecewise linear transfer function described to the model by the
H_array and B_array coordinate pairs. This transfer function does not include hysteretic effects; for
that, you would need to substitute a HYST model for the core. The magnetic flux value Φ in turn is
used by the "lcouple" code model to obtain a value for the voltage reflected back across its terminals
to the driving electrical circuit.
Hysteresis Mode (mode = 2)
In the Hysteresis mode, the model takes a voltage as input which it treats as a magnetomotive force
(mmf) value. This value is used as input to the equivalent of a hysteresis code model block. The
parameters defining the input low and high values, the output low and high values, and the amount of
hysteresis are as in that model. The output from this mode, as in PWL mode, is a current value which
is seen across the magnetic core port.
One final note to be made about the two core models is that certain parameters are specific to one or
the other. In particular, the in_low, in_high, out_lower_limit, out_upper_limit, and hysteresis
parameters are not available in PWL mode. Likewise, the H_array, B_array, area, ad length values
are unavailable in Hysteresis mode. The input_domain and fraction parameters are common to both
modes (though their behavior is somewhat different; for explanation of the input_domain and fraction
values for the Hysteresis mode, please refer to the Hysteresis Block discussion.
Model Identifier: core
Netlist Format:
A<device_name> <mc1 _pin> <mc2_pin> <model_name>
.model <model_name> core area = <value> length = <value> H_array = [<value1> <value2>] B_array
= [<value1> <value2>] {<param1 = value> < param2 = value> ...}
Example:
A1 1 2 core
.model core core area = 1 length = 1 H_array = [0 1] B_array = [0 1]
Parameters:
Name
H_array
B_array
Area
Length
Input_domain
Fraction
Description
magnetic field array
flux density array
cross-sectional area
core length
input smoothing domain
smoothing fraction/abs switch
Default
[0 1]
[0 1]
1
1
0.01
True
Notes
required
required
required
required
Mode
In_low
In_high
Hyst
Out_lower_limit
Out_upper_limit
mode switch (1=pwl, 2=hyst)
input low value
input high value
hysteresis
output lower limit
output upper limit
1
0.0
1.0
0.1
0.0
1.0
The marker serves several purposes:
• It can appear as a default plot in simulations if the "Voltage Probe" box is checked.
• It can be used to set the initial voltage or voltage guess at the node it is connected to.
• It can be used as a port for a subcircuit when you choose the checkbox labeled "Use as
Subcircuit Port" is checked.
• It can be used to explicitly set a node number in place of the arbitrarily assigned node number
by the program. In this case, make sure the "Set Node Index" box is checked. Otherwise, it
will act as just a voltage probe.
• It can be used to connect different parts of a circuit in place of wires. To use markers as virtual
connectors, place them at points where wires would otherwise connect. Then set the Part Title
of the two (or more) markers to the same name, and they will act as a single circuit node.
The MESFET is a Schottky-barrier gate FET with six times greater electron mobility than silicon.
MESFETs are important devices for creating high frequency circuits. They function by creating a
potential barrier between the gate and the channel when the metal gate contacts the gallium-arsenide
substrate. Electron velocity saturates for fields approximately ten times lower than with silicon. The
Curtice model includes linear and saturated operation.
The standard parameters are AREA, OFF, IC, and T. They are described below:
AREA area factor (optional) (If not specified, the default value is 1.0.)
OFF initial condition for the DC analysis (optional)
initial condition (optional) (Used when a transient analysis is desired, which starts from other
IC
than the quiescent operating point.)
T
operating temperature of the device (optional)
All the MESFET process model parameters are described in the following table:
NAME
VTO
BETA
B
ALPHA
LAMBDA
RD
RS
CGS
CGD
PB
KF
AF
FC
PARAMETER
UNITS
pinch-off voltage
V
transconductance parameter
A/V2
doping tail extending parameter
1/V
saturation voltage parameter
1/V
channel-length modulation parameter
1/V
drain ohmic resistance
Ohm
source ohmic resistance
Ohm
zero-bias G-S junction capacitance
F
zero-bias G-D junction capacitance
F
gate junction potential
V
flicker noise coefficient
flicker noise exponent
coefficient for forward-bias depletion capacitance formula -
DEFAULT
-2
1.0e-4
0.3
2
0
0
0
0
0
1
0
1
0.5
EXAMPLE
-2
1.0e-3
0.3
2
1.0e-4
100
100
5pF
1pF
0.6
The MOSFET is an active device that has up to 4 pins. The three standard pins are gate, drain, and
source. These are given in the default symbol. The bulk node, which is grounded by default, is the
fourth pin. The MOSFET with the bulk is named mos_n_lvl1_4 (the lvl1 is for level 1, the n for nmos,
and the 4 for 4 pins.)
The standard parameters are L, W, AD, AS, PD, PS, NRD, NRS, OFF, IC, and T. They are described
below:
L
W
AD,AS
PD,PS
channel length, in meters
channel width, in meters
areas of the drain and source diffusions, in meters2
perimeters of drain and source junctions, in meters(They default to 0.0.)
equivalent number of squares of the drain and source diffusions (These values multiply
NRD,NRS the sheet resistance for an accurate representation of parasitic series drain and source
resistance of each transistor. The default value is 1.0.)
OFF
initial condition for the DC analysis (optional)
initial condition (optional) (Used when a transient analysis is desired, which starts from
IC
other than the quiescent operating point.)
T
operating temperature of the device (optional)
There are five different default models: square-law I-V characteristic, analytical, semi-empirical, and
BSIM and BSIM2 (Berkeley Short-channel IGFET Model), which include second-order effects such as
channel-length modulation, subthreshold conduction, scattering-limited velocity saturation, small-size
effects, and charge-controlled capacitance. The process parameter LEVEL specifies which of the
models is chosen as indicated below:
LEVEL 1
LEVEL 2
LEVEL 3
LEVEL 4
LEVEL 5
LEVEL 6
Schichman-Hodges
MOS2
MOS3
BSIM
BSIM2
MOS6
The process model parameters for levels 1,2,3, and 6 are listed in the following table:
NAME
LEVEL
VTO
KP
GAMMA
PHI
LAMBDA
RD
RS
CBD
CBS
IS
PB
PARAMETER
CJSW
model index
zero-bias threshold voltage
transconductance parameter
bulk threshold parameter
surface potential
channel-length modulation (level 1 & 2 only)
drain ohmic resistance
source ohmic resistance
zero-bias B-D junction capacitance
zero-bias B-S junction capacitance
bulk junction saturation current
bulk junction potential
gate-source overlap capacitance per meter
channel width
gate-drain overlap capacitance per meter
channel width
gate-bulk overlap capacitance per meter
channel length
drain & source diffusion sheet resistance
zero-bias bulk junction bottom capacitance per
meter2 junction area
bulk junction bottom grading coefficient
zero-bias bulk junction sidewall capacitance per
meter junction perimeter
MJSW
bulk junction sidewall grading coefficient
JS
bulk junction saturation current per meter2 of
junction area
oxide thickness
substrate doping
surface state density
fast surface state density
type gate material(+1 if opp. substrate, 0 if A1
gate, -1 if same as substrate)
metallurgical junction depth
lateral diffusion
surface mobility
critical field for mobility degradation (level2 only)
critical field exponent in mobility degradation
(level2 only)
transverse field coefficient (deleted for level2)
maximum drift velocity of carriers
CGSO
CGDO
CGBO
RSH
CJ
MJ
TOX
NSUB
NSS
NFS
TPG
XJ
LD
UO
UCRIT
UEXP
UTRA
VMAX
UNITS
DEFAULT
EXAMPLE
V
A/V2
V1/2
V
1/V
ohms
ohms
F
F
A
V
1
0.0
2e-5
0.0
0.6
0.0
0.0
0.0
0.0
0.0
1.0e-14
0.8
1.0
3.1e-5
0.37
0.65
0.02
1.0
1.0
20fF
20fF
1.0e-15
0.87
F/m
0.0
4.0e-11
F/m
0.0
4.0e-11
F/m
0.0
2e-10
ohm/area 0.0
10.0
F/m2
0.0
2e-4
0.5
0.5
0.0
1.0e-9
F/m
0.5, 0.33 (level1),
(level2,3)
A/m2
meter
1/cm3
1/cm2
1/cm2
1.0e-8
1.0e-7
0.0
0.0
0.0
1.0e-7
4.0e15
1.0e10
1.0e10
1.0
meter
meter
cm2/Vs
V/cm
m/s
0.0
0.0
600
1.0e4
1
0.8
700
1.0e4
0.0
0.1
0.0
0.0
0.3
5.0e4
NEFF
KF
AF
FC
DELTA
THETA
ETA
KAPPA
TNOM
total channel-charge (fixed and mobile)
coefficient (level2 only)
flicker noise coefficient
flicker noise exponent
coefficient for forward bias depletion
capacitance formula
width effect on threshold voltage (level2,3)
mobility modulation (level3 only)
static feedback (level3 only)
saturation field factor (level3 only)
parameter measurement temperature
1.0
5.0
0.0
1.0
1.0e-26
1.2
0.5
1/V
deg. C
0.0
0.0
0.0
0.2
27
1.0
0.1
1.0
0.5
50
The BSIM model has no default parameters, and leaving one out is considered an error. The
additional process model parameters for level 4 and 5 models are listed in the following table:
NAME
VFB
PHI
K1
K2
ETA
MUZ
DL
DW
U0
U1
X2MZ
X2E
X3E
X2U0
X2U1
MUS
X2MS
X3MS
X3U1
TOX
TEMP
VDD
CGDO
CGSO
CGBO
XPART
N0
NB
ND
RSH
JS
PB
MJ
PBSW
PARAMETER
flat-band voltage
surface inversion potential
body effect coefficient
drain/source depletion charge-sharing coefficient
zero-bias drain-induced barrier-lowering coefficient
zero-bias mobility
shortening of channel
narrowing of channel
zero-bias transverse-field mobility degradation coefficient
zero-bias velocity saturation coefficient
sens. of mobility to substrate bias at Vds=0
sens. of drain-induced barrier lowering effect to substrate bias
sens. of drain-induced barrier lowering effect to drain bias at Vds= Vdd
sens. of transverse field mobility degradation to substrate bias
sens. of velocity saturation effect to substrate bias
mobility at zero substrate bias and at Vds= Vdd
sens. of mobility to substrate bias at Vds= Vdd
sens. of mobility to drain bias at Vds= Vdd
sens. of velocity saturation effect on drain bias at Vds= Vdd
gate oxide thickness
temperature at which parameters were measured
measurement bias range
gate-drain overlap capacitance per meter channel width
gate-source overlap capacitance per meter channel width
gate-bulk overlap capacitance per meter channel length
gate-oxide capacitance-charge model flag
zero-bias subthreshold slope coefficient
sens. of subthreshold slope to substrate bias
sens. of subthreshold slope to drain bias
drain and source diffusion sheet resistance
source drain junction current density
built-in potential of source drain junction
grading coefficient of source drain junction
built-in potential of source drain junction sidewall
UNITS
V
V
V1/2
cm2/V-s
m
m
V-1
m/V
cm2/V2-s
V-1
V-1
V-2
mV-2
cm2/V2-s
cm2/V2-s
cm2/V2-s
mV-2
m
deg. C
V
F/m
F/m
F/m
ohms/area
A/m2
V
V
MJSW grading coefficient of source drain junction sidewall
CJ
source drain junction capacitance per unit area
F/ m2
CJSW source drain junction sidewall capacitance per unit length
F/m
WDF source drain junction default width
m
DELL source drain junction length reduction
m
XPART=0 selects a 40/60 drain/source charge partition; XPART=1 selects a 0/100 partition.
The Multiplier Block has two inputs. Each input is added to its respective offset and then multiplied by
the specified input gain (with default values of 1). These are then multiplied along with the output gain
and the result is added to the output offset. Note that the input offsets and input gains are specified as
vectors. The multiplier function operates in DC, AC, and Transient analysis modes. In AC analysis,
however, it is important to remember that results are invalid unless one of the inputs is a DC voltage.
Model Identifier: mult
Netlist Format:
A<device_name> [<in_pin1> <in_pin2> {...}] <out_pin> <model_name>
.model <model_name> mult {<param1 = value> < param2 = value> ...}
Example:
A1 [1 2] 3 mult_block
.model mult_block mult in_offset = [0.0 0.0] in_gain = [1.0 1.0] out_gain = 1.0 out_offset = 0.0
Parameters:
Name
in_offset
in_gain
out_gain
out_offset
Description
input offset vector
input gain vector
output gain
output offset
Default
[0.0 0.0]
[1.0 1.0]
1.0
0.0
The mutual inductor is a pair of inductors that are coupled. L1 and L2 are the names of two inductors.
Specify the inductance of inductor L1, the inductance of inductor L2, the initial current through each,
and the coupling coefficient.
Nonlinear dependent (arbitrary) sources use an equation or mathematical expression to describe their
behavior. One and only one of the two forms: V=<expr> or I=<expr> must be given.
Netlist Format:
B<device_name> v = <expression>
B<device_name> i = <expression>
Examples:
v = I(v1) + 3* I(v2)
I = v(i1) + 3* v(2) + 5 * v(3) ^2
The first example is a current-controlled voltage source. The v on the left side of the equation
indicates that it is a voltage source. I(v1) and I(v2) are the currents through voltage sources named v1
and v2, respectively.
The second example is a voltage-controlled current source. v(2) and v(3) represents the voltages at
nodes 2 and 3, respectively, and v(i1) represents the voltage across a current source named i1.
The following mathematical functions defined for real variables can be used in the expressions:
abs, acos, acosh, asin, asinh, atan, atanh, cos, cosh, exp, ln, log, sin, sinh, sqrt, tan.
The function "u" is the unit step and "uramp" is the integral of the unit step. The unit step is one if its
argument is greater than zero and zero if its argument is less than zero. The ramp function (uramp) is
0 for argument values less than zero and equal to the argument for argument values greater than
zero.
The following operators are permissible: +, -, *, /, ^, and unary-.
To get time into an expression, integrate the current from a constant current source with a capacitor
and use the voltage across the capacitor.
The nonlinear resistor model allows the resistor to described by a table relating I to V, where I is the
current through the resistor, and V is the voltage across the resistor.
The Non-linear conductor: This model allows the conductor to described by a table relating I to V,
where I is the current through the conductor, and V is the voltage across the conductor.
The non-linear capacitor model allows the capacitor to described by a table relating V to Q, where Q
is the charge contained in the capacitor, and V is the voltage across the capacitor. C, the non-linear
capacitance, is defined as dQ/dV.
The non-linear inductor model allows the inductor to described by a table relating I to Flux, where
Flux is the flux in the inductor, and I is the current across the inductor. L, the non-linear inductance, is
defined as d Flux / dI.
This component is an amplifier with very high voltage gain, very high input impedance and very low
output impedance.
The Op Amp in the devices menu is based on the algorithm found in the book Macromodeling with
Spice, authored by Connelly & Choi, published by Prentice Hall, section 3.3. The parameters for
the default op-amp are those of the 741 op-amp. The Op Amp model is converted from a set of
parameters which you enter into the program, into a subcircuit. The +VS pin should be connected to
positive power, and the negative vertical pin should be connected to negative power to properly
power the Op Amp. Sometimes, if the circuit is not converging, the reason will be that the power
supplies are hooked up backwards. To check which power supply is supposed to be positive, choose
the Show Pin Names option in the Edit menu's Options dialog. Also, sometimes the simulation
doesn't converge if there is no DC path from the output of the Op Amp to ground.
There are many more op-amps from parts vendors. To see a list, browse the parts, and set the
category filter to opamp, and apply filter.
OpAmp parameters
NAME
dm_res_in
cm_res_in
DC_dm_gain
CMRR
in_off_curr
in_bias_curr
res_out
pos_slew
neg_slew
cap_in
off_volt_in
f_pole1
f_pole2
f_pole3
f_zero
f_pole4
curr_src_max
PARAMETER
Differential mode input resistance
Common mode input resistance
DC differential mode gain
Common mode rejection ratio
Input offset current
Input bias current
Output resistance
Positive slew rate
Negative slew rate
Input capacitance
Input offset voltage
Frequency of the first pole
Frequency of the second pole
Frequency of the third pole
Frequency of the zero
Frequency of the fourth pole
Maximum source current
UNITS
OHM
OHM
dB
dB
A
A
OHM
V/us
V/us
F
V
Hz
Hz
Hz
Hz
Hz
A
curr_sink_
input_type
Maximum sink current
input type (n or p)
A
The Piecewise Linear (PWL) Controlled Source is a single-input and single-output function generator
whose output is not necessarily linear for all input values. Instead, it follows an I/O relationship that is
specified by the x_array and y_array coordinates. The x_array and y_array values represent vectors
of coordinate points on the x and y axes, respectively. The x_array values are progressively
increasing input coordinate points, and the associated y_array values represent the outputs at those
points. There may be as few as two pairs specified, or as many as memory and simulation speed
allow.
In order to fully specify outputs for values of Vin outside of the bounds of the PWL function, the PWL
controlled source model extends the slope found between the lowest two coordinate pairs and the
highest two coordinate pairs. This has the effect of making the transfer function completely linear for
Vin less than x_array[0] and Vin greater than x_array[n]. It also has the potentially subtle effect of
unrealistically causing an output to reach a very large or small value for large inputs. You should thus
keep in mind that the PWL Source does not inherently provide a limiting capability.
In order to diminish the potential for divergence of simulations when using the PWL block, a form of
smoothing around the x_array and y_array coordinate points is necessary. This is due to the iterative
nature of the simulator and its reliance on smooth first derivatives of transfer functions in order to
arrive at a matrix solution. Consequently, the two parameters "input_domain" and "fraction" are
included to allow you some control over the amount and nature o the smoothing performed.
Fraction is a switch that is either TRUE or FALSE. When TRUE (the default setting), the simulator
assumes that the specified input_domain value is to be interpreted as a fractional figure. Otherwise, it
is interpreted as an absolute value. Thus, if fraction = TRUE and input_domain = 0.10, the simulator
assumes that the smoothing radius about each coordinate point is to be set equal to 10% of the
length of either the x_array segment above each coordinate point, or the x_array segment below
each coordinate point. The specific segment length chosen will be the smallest of these two for each
coordinate point.
If fraction = FALSE and input_domain = 0.10, then the simulator will begin smoothing the transfer
function at 0.10 volts (or amperes) below each x_array coordinate and will continue the smoothing
process for another 0.10 volts (or amperes) above each x_array coordinate point.
Model Identifier: pwl
Netlist Format:
A<device_name> %vd(<in_pin> <in_ref_pin>) %vd(<out_pin> <out_ref_pin>) <model_name>
.model <model_name> pwl x_array = [<value1> <value2> ...] y_array = [<value1> <value2> ...]
{<param1 = value> < param2 = value> ...}
Example:
A1 %vd(2 3) %vd(1 4) pwl .model pwl pwl x_array = [0 1] y_array = [0 1]
Parameters:
Name
x_array
y_array
input_domain
fraction
Description
x-element array
y-element array
input smoothing domain
smoothing %/abs switch
Default Notes
[0 1]
required
[0 1]
required
0.01
True
Resistors are passive devices that dissipate power. Their resistance value varies depending on how
much power they can dissipate and is measured in Ohms. The transient, DC and AC behaviors of a
resistor are all described by the same equation:
v=R*i
where v is the voltage across the resistor, i is the current passing through the resistor, and R is the
resistance. The value of R must be nonzero.
All resistor names must begin with R.
Netlist Format:
R<device_name> <N+> <N-> <value>
Example:
R1 1 2 1k
B2.Spice A/D provides three types of resistor: Simple, User-Defined (Real Resistor) and
Semiconductor.
Simple Resistor
The resistance of the simple resistor is a single value. You can also set the Monte Carlo tolerance for
this resistor.
User-Defined Resistor
This is primarily a temperature-dependent resistor. You can access it from the Parts Menu. It has two
process model parameters: TC1 first-order temperature coefficient, and TC2 second-order
temperature coefficient. The value of the temperature-dependent resistance is computed using the
quadratic equation:
R(T) = R(T0) * [ 1 + TC1 * (T - T0) + TC2 * (T-T0)^2 ]
Semiconductor Resistor
This allows for both the modeling of temperature effects and the calculation of resistance from
geometric characteristics and the specifications of the process in the model specification of the
resistor. If width isn't specified, then the default width given in the model is used. The temp value is
the temperature and it's optional. If it's not given, the temperature in the .Options line will be used.
The model parameters are as follows: TC1, first order temperature coefficient; TC2, second order
temperature coefficient; RSH, sheet resistance; DEFW, default width; TNOM, the parameter
measurement temperature; NARROW, narrowing due to side etching, and RES, the resistance
multiplier for Monte Carlo analysis. To modify the model parameters, first double click on the resistor
to edit its top-level model parameters, then choose the button in the process model section to Edit
from table and this will open a window in which you can edit TC1, TC2, RSH, RES, etc.
The resistance is computed as:
R(T0) = (RSH) * [(L - NARROW) / (W - NARROW)] * RES
R(T) = R(T0) * [ 1 + TC1 * (T - T0) + TC2 * (T-T0)^2 ]
The s-domain transfer function is a single input and output transfer function in the Laplace transform
variable \93s\94 that allows for flexible modulation of the frequency-domain characteristics of a signal.
The code model may be configured to produce an arbitrary s-domain transfer function with the
following restrictions:
1.
The degree of the numerator polynomial cannot exceed that of the denominator polynomial in
the variable \93s\94.
2.
The coefficients for a polynomial must be stated explicitly. That is, if a coefficient is zero, it must
be included as an input to the num_coeff or den_coeff vector.
Gain and input offset parameters are included to allow for tailoring of the required signal. Internal
signal values and the output value of the s-domain transfer function do not have limits, so you are
cautioned to specify gain and coefficient values that will not cause the model to produce excessively
large values. In AC analysis, the value returned is equal to the real and imaginary components of the
total s-domain transfer function at each frequency of interest.
The denormalized_freq term allows you to specify coefficients for a normalized filter (i.e., one in which
the frequency of interest is 1 rad/s) Once these coefficients are included, specifying the denormalized
frequency value \93shifts\94 the corner frequency to the actual one of interest.
Truncation error checking is included in the s-domain transfer block. This should provide for more
accurate simulations, since the model will inherently request smaller time increments between
simulations points if truncation errors would otherwise be excessive.
The order of the coefficient parameters is from that associated with the highest-powered term
decreasing to that of the lowest.
Model Identifier: s_xfer
Netlist Format:
A<device_name> <in_pin> <out_pin> <model_name>
.model <model_name> s_xfer num_coeff = [<value1> {<value2>}...] den_coeff = [<value1>
{<value2>}...]
+
int_ic = [<value1> {<value2>}...] {<param1 = value> < param2 = value> ...}
Example:
A 1 2 A_transfer_function
.model A_transfer_function s_xfer num_coeff = [1] den_coeff = [1] int_ic = [0.0]
Parameters:
Name
In_offset
Gain
Num_coeff
Den_coeff
Int_ic
Denormalized_freq
Description
input offset
gain
numerator polynomial coefficients
denominator polynomial coefficients
integrator stage initial conditions
denormalized corner freq. (radians) for 1 rad/s coeffs
Default
0.0
1.0
[1]
[1]
[0.0]
1.0
Notes
required
required
required
The Summer Block has two inputs. Each input is added to its respective offset and then multiplied by
the specified input gain (with default values of 1). These are then summed, multiplied by the output
gain and added to the output offset. Note that the input offsets and input gains are specified as
vectors. The summer function operates in DC, AC, and Transient analysis modes.
Model Identifier: summer
Netlist Format:
A<device_name> <in_pin> <out_pin> <model_name>
.model <model_name> summer {<param1 = value> < param2 = value> ...}
Example:
A1 [1 2] 3 summer
.model summer summer in_offset = [0 0] in_gain = [1 1] out_gain = 1.0 out_offset = 0.0
Parameters:
Name
in_offset
in_gain
out_gain
out_offset
Description
input offset vector
input gain vector
output gain
output offset
Default
[0 0]
[1 1]
1.0
0.0
The Thermometer is a two-pin device that measures the operating temperature of a circuit. The
voltage across the device pins is equal to SPICE's operating temperature in degrees centigrade. The
output voltage of the Thermometer can be used in conjunction with linear or nonlinear dependent
sources to model temperature-dependent quantities.
Model Identifier: thermo
Parameters:
This device has no parameters.
Transmission lines are bi-directional, ideal delay lines, with A and B ports, and + and - port nodes,
which define the polarity of a positive voltage at that port. The transmission line's length can be
specified either by TD (a delay in seconds), or by F and NL (a frequency and the corresponding
relative wavelength).
During transient analysis, the internal step time is limited to no more than \BD the smallest time delay.
Thus short transmission lines lead to long run times.
Transmission lines can be of three main types, Lossless, Lossy or Uniform RC. Each of these is
described in its own section.
The standard parameters are L, and N. They are described below:
Two of the nodes are the element nodes connected by the RC line. The third is the node to which the
capacitances are connected. L is the length of the RC line in meters. N is the number of lumped
segments to use in modeling the RC line.
This device is derived from a model proposed by Gertzberrg. It expands the URC line into a network
of lumped RC segments with internally generated nodes. These segments increase toward the
middle of the URC line in a geometric progression with K as the proportionality constant.
The URC line is made up entirely of resistor and capacitor segments, unless the ISPERL parameter
has a non-zero value. In this case, capacitors are replaced by reverse biased diodes with an
equivalent zero-bias junction capacitance, a saturation current of ISPERL amps per meter of
transmission line, and optional series resistance of RSPERL ohms per meter. Parameters are giving
in the chart below:
NAME
K
FMAX
RPERL
CPERL
ISPERL
RSPERL
PARAMETER
propagation constant
maximum frequency of interest
resistance per unit length
capacitance per unit length
saturation current per unit length
diode resistance per unit length
UNITS DEFAULT
2
Hz
1.0G
Ohm /m 1000
F/m
1.0e-15
A/m
0
Ohm/m 0
EXAMPLE
1.2
6.5Meg
10
1pF
-
Switches are devices that exhibit high resistance when open (OFF state) and low resistance when
closed (ON state). The switch model allows an almost ideal switch to be specified. With careful
selection of the on and off resistances, they can effectively represent zero and infinite resistances in
comparison to other circuit elements, while sustaining the model condition of a positive, finite value.
There are two versions of Voltage-Controlled Switch: two-terminal and four-terminal. For the
two-terminal device, you must specify the name of the controlling Voltmeter or controlling voltage
nodes, as well as the turn-on and turn-off voltages in Volts and on and off resistance values in Ohms.
The four-terminal device already provides nodes for a controlling voltmeter, and you just specify the
rest of parameters. When the voltage across the switch or controlling device is greater or equal to the
turn-on current, the switch closes. When the voltage across the switch or controlling device is less
than or equal to the turn off current, the switch opens.
NAME
V_ON
V_OFF
RON
ROFF
PARAMETER
turn-on voltage
turn-off voltage
on resistance
off resistance
UNITS
Volts
Volts
ohms
ohms
DEFAULT
0.5
0.0
1.0
1Gig
XSpice devices have the following form:
A<device_name> <node1> <node2> ... <model_name>
e.g., A2 1 2 transfer_function Note that XSpice devices must start with the "A" designation, much as a
resistor starts with an "R". Some devices will have grouped (or vector) pins and are designated by
being placed inside square brackets. In the example shown below, the 1 and 2 pins are grouped. Pin
3 is not.
A1 [1 2] 3 summer
Some models will have voltage differential pairs of pins and will be denoted by a %vd( ). In the
following example pins 1 and 4 are differential pairs, as well as pins 2 and 3. Differential pairs must
go between parentheses ().
A1 %vd(1 4) %vd(2 3) triangle
Refer to individual devices for more information.
Each XSpice device will also have a model associated with it. Each model will have the following
form:
.model <model_name> <model_identifier> {<pname1 = pval1>} {<pname2 = pval2>} ...
e.g., .model transfer_function s_xfer in_offset = 0.0 gain = 1.0
Model_name refers to the name given in the device line. Model_identifier is an internal designation
and must be of an existing designation Refer to each device's example for the correct designation.
Parameter values are optional. If they aren't specified, then the default will be used. Some devices
have parameters that require a value and must be specified. Refer to individual devices for any
required parameters.
The Zener Diode models the DC characteristics of most zeners. Since most data sheets for zener
diodes do not give detailed characteristics in the forward region, only a single point defines the
forward characteristicThe saturation current refers to the relatively constant reverse current that is
produced when the voltage across the zener is negative, but breakdown has not been reached. The
reverse leakage current determines the slight increase in reverse current as the voltage across the
zener becomes more negative. It is modeled as a resistance parallel to the zener with value
v_breakdown / i_rev.
Note that the limt_switch parameter engages an internal limiting function for the zener. This can, in
some cases, prevent the simulator from converging to an unrealistic solution if the voltage across or
current into the device is excessive. If use of this feature fails to yield acceptable results, the convlimit
option should be tried (add the following statement to the SPICE input deck: .options convlimit)
Model Identifier: zener
Netlist Format:
A<device_name> <z_pin> <z_out_pin> <model_name>
.model <model_name> zener v_breakdown = 1 {<param1 = value> < param2 = value> ...}
Example:
A1 1 2 zener
.model zener zener v_breakdown = 1
Parameters:
Name
v_breakdown
i_breakdown
i_sat
N_forward
limit_switch
Description
breakdown voltage
breakdown current
saturation current
forward emission coefficient
switch for on-board limiting (convergence aid)
List of B2.Spice A/D Keyboard Shortcuts
of Generic Digital and Mixed-Mode Devices
Default Notes
1
required
2.0e-2
1.0e-12
1.0
False
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