AC Simulation
and Noise Contributions
ADS 2009 (version 1.0)
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Slide 4 - 1
AC Simulation
ADS 2009 (version 1.0)
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Slide 4 - 2
AC Simulation Controller
ADS 2009 (version 1.0)
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Slide 4 - 3
AC Noise calculations
Nodes for noise
are Wire/Pin
Labels.
Sort by name
or by value:
in the dataset.
Blank gives you
all contributors.
ADS 2009 (version 1.0)
Copyright Agilent Technologies 2009
Slide 4 - 4
AC sources are for AC simulations
•  V_AC, P_AC, and I_AC are component names.
•  SRC3, PORT1, and SRC4 are instance names
which you can change.
•  Vac = polar (1,0)V is the default value.
The polar function can be removed (next slide).
•  Freq = freq is a global variable - you set the start
& stop values in the simulation controller.
•  P sources are also ports (ok for S-parameter)
•  Num=1 is the port number.
•  I current sources can be used for other
simulations to inject current.
•  Arrow in symbol shows the direction
of current flow.
ADS 2009 (version 1.0)
Copyright Agilent Technologies 2009
Slide 4 - 5
Setting AC source values
POWER: The dbmtow function
converts power in dbm to power in
watts for the simulator.
PHASE: The polar function specifies
phase. By default, all sources are
cosine waves. Use -90 for a
sinewave.
NOISE and Vdc: By default, noise is
turned on for the P_AC source. Use
Display tab/settings to make visible.
Vdc 10 mV is an offset (superposition).
Equations can also be used: P=1W, P=1+j*1W, P=complex(1,0), etc.
ADS 2009 (version 1.0)
Copyright Agilent Technologies 2009
Slide 4 - 6
Summary of ADS equation types
•  VAR: pre-simulation
Use for initializing sweep variables or
other settings. VARs are available in
the dataset if you select them in the
schematic
Output tab of the simulation controller.
•  MeasEqn: pre-simulation
Use on schematic pre-simulation and it
is available in the dataset after
simulation. It uses node labels and
functions.
•  Eqn: post-simulation -
data display
Use for calculations in the data
display. Use node voltages,
functions, and any dataset data.
ADS 2009 (version 1.0)
Copyright Agilent Technologies 2009
Slide 4 - 7
Review of Data Display equation editor
Insert button gives full path (dataset..) if not the default.
Click here for
DDS equations:
Schematic MeasEqns
appear in the dataset.
Click Functions Help = on-line manuals:
Functions (measurement expressions) are
defined with examples…
Invalid equations are red:
Valid equations are black:
ADS 2009 (version 1.0)
Copyright Agilent Technologies 2009
Slide 4 - 8
Printing ADS schematics and data
Print… shows printer
name, type (most HP
Desk Jets & Laser Jets).
Use Properties for
colors, size, orientation,
etc. Export JPG, BMP,
GIF to Windows tools.
ADS 2009 (version 1.0)
Copyright Agilent Technologies 2009
Slide 4 - 9
Stopping an ADS processes
If your computer is locked up or if there is any other problem
(Data Display), you can safely stop some processes:
hpeesofde.exe - closes the ADS program (same as exit)
hpeesofsim.exe - stops the simulation or in schematic:
hpeesofdds.exe – ends the data display server
UNIX users kill processes - PC users end processes
PC task manager NT: ctrl-alt-delete
In a UNIX window,
use: ps -ef | tail
and you can kill (xxx)
a processes.
ADS 2009 (version 1.0)
Copyright Agilent Technologies 2009
Slide 4 - 10
Useful Data Display features...
•  Copy/Paste: Ctrl C copies / Ctrl V pastes
•  ALSO for the Data Display:
- Hot Keys & Predefined Equations
HOT KEY and DDS
command to your
keyboard for efficiency
and speed - similar to
schematic Hot Keys!
ADS 2009 (version 1.0)
Copyright Agilent Technologies 2009
Document
your plots!
Slide 4 - 11
Lab 4:
AC Simulations and
Noise Contributions
ADS 2009 (version 1.0)
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Slide 4 - 12
Steps in the Design Process
You are here:
ADS 2009 (version 1.0)
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•  Design the RF sys behavioral model receiver
•  Test conversion gain, spectrum, etc.
•  Start amp_1900 design – subckt parasitics
•  Simulate amp DC conditions & bias network
•  Simulate amp AC response - verify gain
•  Test amp noise contributions
•  Simulate amp S-parameter response
•  Create a matching topology
•  Optimize the amp in & out matching networks
•  Filter design – lumped 200MHz LPF
•  Filter design – microstrip 1900 MHz BPF
•  Transient and Momentum filter analysis
•  Amp spectrum, delivered power, Zin - HB
•  Test amp comp, distortion, two-tone, TOI
•  CE basics for spectrum and baseband
•  CE for amp_1900 with GSM source
•  Replace amp and filters in rf_sys receiver
•  Test conversion gain, NF, swept LO power
•  Final CDMA system test CE with fancy DDS
•  Co-simulation of behavioral system
Slide 4 - 13
Simulation setup with Noise
Noise is turned on and the noise node defined.
NOTE: By default, the AC controller sweeps the
global variable freq using the settings shown and
ignores any setting in the source.
ADS 2009 (version 1.0)
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Slide 4 - 14
Set up a Meas Eqn and Outputs...
Generic Meas Eqn from any simulation palette:
Use the Controller Output tab (works the
same in all controllers) to specify which
simulation data is output to the dataset.
Here, Vcc Is eliminated from the dataset.
NOTE: You can attach specific equations to specific simulation controllers,
using the Display tab and checking the box for:
ADS 2009 (version 1.0)
Copyright Agilent Technologies 2009
Slide 4 - 15
Operate on data: equations & functions
Write an equation
using the editor.
List the Meas Eqn & DDS equation:
Operate directly on listed or plotted data
by typing in a function (dB):
Edit and change to another plot type:
ADS 2009 (version 1.0)
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Slide 4 - 16
Plot phase and calculated group delay
Plot the phase of Vin and Vout:
Calculate group delay with an
equation using Phase data. Also,
control marker readout formats:
ADS 2009 (version 1.0)
Copyright Agilent Technologies 2009
Slide 4 - 17
Variables and the what function…what?
•  Insert a list of Vout
•  Click on: Trace Options
•  Then click: Variable Info…
The value of a dataset
item, such as a node
voltage, depends on its
variables: Vout here is
dependent on the ADS
freq variable.
Or, use the what function on any data and get the same information this will be useful later when the data becomes more dependent:
Next, sweeping
parameters…
ADS 2009 (version 1.0)
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Slide 4 - 18
Parameter Sweep: bias voltage
AC simulation with a parameter sweep
component to sweep a VAR: Vbias.
Type in the freq
for the marker!
Explicit dataset path uses ..
Understanding the data…
ADS 2009 (version 1.0)
Copyright Agilent Technologies 2009
Slide 4 - 19
Understanding Lab Results: data
Concept: data in dataset is a function of one or more variables,
and all data is indexed beginning with index value 0.
Sweep DC bias and AC frequency: Vout is a function of V_bias and freq: Vout [V_bias,freq]
Index
for freq:
Index for
V_bias = 0
if 2V is the
first value.
0
1
2
3
4
5
6
•  Vout returns all data, for all index values 0 through N of each sweep
•  Vout[0,1] returns V_bias only at index 0, and freq only at index 1
•  Vout[::,1] returns all values of V_bias, and freq at index 1
•  Vout[0,::] returns V_bias at index 0, and all values of freq
•  Vout[0::2::6,::] returns V_bias at index values 0, 2, 4, 6 and all values of freq
SYNTAX NOTE: Double colon :: is equivalent to “all values” like a wildcard.
For example[a::b::c] a=start, b=increment, c=stop.
More information in Data Display manual:Working with Multidimensional Data
ADS 2009 (version 1.0)
Copyright Agilent Technologies 2009
Slide 4 - 20
Parameter Sweep of voltage
For an AC simulation, use a parameter
sweep component to sweep a VAR: Vbias.
Type in the freq
for the marker!
Explicit dataset path uses ..
Start the
lab now!
ADS 2009 (version 1.0)
Copyright Agilent Technologies 2009
Slide 4 - 21
ADS 2009 (version 1.0)
Copyright Agilent Technologies 2009
Slide 4 - 22