®
OPA2111
Dual Low Noise Precision
Difet ® OPERATIONAL AMPLIFIER
FEATURES
APPLICATIONS
● LOW NOISE: 100% Tested, 8nV/√Hz max at
10kHz
● PRECISION INSTRUMENTATION
● DATA ACQUISITION
● TEST EQUIPMENT
●
●
●
●
●
LOW BIAS CURRENT: 4pA max
LOW OFFSET: 500µV max
LOW DRIFT: 2.8µV/°C
HIGH OPEN-LOOP GAIN: 114dB min
HIGH COMMON-MODE REJECTION:
96dB min
● PROFESSIONAL AUDIO EQUIPMENT
● MEDICAL EQUIPMENT
● DETECTOR ARRAYS
DESCRIPTION
The OPA2111 is a high precision monolithic
dielectrically isolated FET (Difet ) operational amplifier. Outstanding performance characteristics allow its
use in the most critical instrumentation applications.
Noise, bias current, voltage offset, drift, open-loop
gain, common-mode rejection, and power supply rejection are superior to BIFET® amplifiers.
Very low bias current is obtained by dielectric isolation with on-chip guarding.
+VCC
8
–In
+In
Noise-Free
Cascode*
Laser trimming of thin-film resistors gives very low
offset and drift. Extremely low noise is achieved with
patented circuit design techniques. A cascode design
allows high precision input specifications and reduced
susceptibility to flicker noise.
Standard dual op amp pin configuration allows upgrading of existing designs to higher performance
levels.
Output
–VCC
4
*Patented
OPA2111 Simplified Circuit
(Each Amplifier)
BIFET® National Semiconductor Corp., Difet ® Burr-Brown Corp.
International Airport Industrial Park • Mailing Address: PO Box 11400
Tel: (520) 746-1111 • Twx: 910-952-1111 • Cable: BBRCORP •
• Tucson, AZ 85734 • Street Address: 6730 S. Tucson Blvd. • Tucson, AZ 85706
Telex: 066-6491 • FAX: (520) 889-1510 • Immediate Product Info: (800) 548-6132
© 1984 Burr-Brown Corporation
PDS-540E
Printed in U.S.A. October, 1993
SPECIFICATIONS
ELECTRICAL
At VCC = ±15VDC and TA = +25°C unless otherwise noted
.
OPA2111AM
PARAMETER
CONDITION
INPUT NOISE
Voltage, fO = 10Hz
fO = 100Hz
fO = 1kHz
fO = 10kHz
fB = 10Hz to 10kHz
fB = 0.1Hz to 10Hz
Current, fB = 0.1Hz to 10Hz
fO = 0.1Hz to 20kHz
OFFSET VOLTAGE(2)
Input Offset Voltage
Average Drift
Match
Supply Rejection
MIN
100% Tested
100% Tested
100% Tested
(1)
(1)
(1)
(1)
(1)
VCM = 0VDC
TA = TMIN to TMAX
90
OPA2111BM
TYP
MAX
40
15
8
6
0.7
1.6
15
0.8
MIN
OPA2111SM
TYP
MAX
80
40
15
8
1.2
3.3
24
1.3
30
11
7
6
0.6
1.2
12
0.6
±0.1
±2
±1
110
±3
136
±0.75
±6
96
±31
MIN
OPA2111KM, KP
TYP
MAX
60
30
12
8
1
2.5
19
1
40
15
8
6
0.7
1.6
15
0.8
80
40
15
8
1.2
3.3
24
1
40
15
8
6
0.7
1.6
15
0.8
±0.05
±0.5
±0.5
110
±3
136
±0.5
±2.8
±0.1
±2
2
110
±3
136
±0.75
±6
±0.3
±8
2
110
±3
136
90
±16
MIN
86
±31
TYP
MAX
UNITS
nV/√Hz
nV/√Hz
nV/√Hz
nV/√Hz
µVrms
µVp-p
fAp-p
fA/√Hz
±2
±15
±50
mV
µV/°C
µV/°C
dB
µV/V
dB
Channel Separation
100Hz, R L = 2kΩ
BIAS CURRENT(2)
Input Bias Current
Match
VCM = 0VDC
±2
±1
±8
±1.2
±0.5
±4
±2
±1
±8
±3
2
±15
pA
pA
VCM = 0VDC
±1.2
±6
±0.6
±3
±1.2
±6
±3
±12
pA
OFFSET CURRENT(2)
Input Offset Current
IMPEDANCE
Differential
Common-Mode
1013 || 1
1014 || 3
VOLTAGE RANGE
Common-Mode Input Range
Common-Mode Rejection
1013 || 1
1014 || 3
1013 || 1
1014 || 3
1013 || 1
1014 || 3
Ω || pF
Ω || pF
VIN = ±10VDC
±10
90
±11
110
±10
96
±11
110
±10
90
±11
110
±10
82
±11
110
V
dB
RL ≥ 2kΩ
110
125
3
114
125
2
110
125
3
106
125
3
dB
dB
FREQUENCY RESPONSE
Unity Gain, Small Signal
Full Power Response
Slew Rate
Settling Time, 0.1%
0.01%
Overload Recovery,
50% Overdrive(3)
20Vp-p, RL = 2kΩ
VO = ±10V, RL = 2kΩ
Gain = –1, RL = 2kΩ
10V Step
16
1
2
32
2
6
10
2
32
2
6
10
MHz
kHz
V/µs
µs
µs
5
5
µs
RATED OUTPUT
Voltage Output
Current Output
Output Resistance
Load Capacitance Stability
Short Circuit Current
RL = 2kΩ
VO = ±10VDC
DC, Open-Loop
Gain = +1
±11
±10
100
1000
40
V
mA
Ω
pF
mA
±15
VDC
OPEN-LOOP GAIN, DC
Open-Loop Voltage Gain
Match
Gain = –1
POWER SUPPLY
Rated Voltage
Voltage Range, Derated
Performance
Current, Quiescent
2
32
2
6
10
16
1
5
±10
±5
10
±11
±10
100
1000
40
±5
5
16
1
5
±10
±5
10
±15
IO = 0mADC
2
32
2
6
10
±11
±10
100
1000
40
±10
±5
10
±15
±18
7
±5
5
±11
±10
100
1000
40
±10
±5
10
±15
±18
7
±5
5
±18
7
±5
0
–55
–40
–65
–40
5
±18
9
VDC
mA
+70
+125
+85
+150
+85
°C
°C
°C
°C
°C
°C/W
TEMPERATURE RANGE
Specification
Operating “M” Package
“P” Package
Storage “M” Package
“P” Package
θ Junction-Ambient
Ambient Temp.
Ambient Temp.
–25
–55
+85
+125
–25
–55
+85
+125
–55
–55
+125
+125
Ambient Temp.
–65
+150
–65
+150
–65
+150
200
200
200
200(4)
NOTES: (1) Sample tested—this parameter is guaranteed. (2) Offset voltage, offset current, and bias current are measured with the units fully warmed up. (3) Overload
recovery is defined as the time required for the output to return from saturation to linear operation following the removal of a 50% input overdrive. (4) Typical θJ-A =
150°C/W for plastic DIP.
®
OPA2111
2
ELECTRICAL (FULL TEMPERATURE RANGE SPECIFICATIONS)
At VCC = ±15VDC and TA = TMIN to TMAX unless otherwise noted.
OPA2111AM
PARAMETER
TEMPERATURE RANGE
Specification Range
CONDITION
MIN
Ambient Temp.
–25
INPUT OFFSET VOLTAGE(1)
Input Offset Voltage
Average Drift
Match
Supply Rejection
VOLTAGE RANGE
Common-Mode Input Range
Common-Mode Rejection
+85
–25
TYP
OPA2111SM
MAX
MIN
+85
–55
VCM = 0VDC
±125
60
±1nA
±75
30
±500
VCM = 0VDC
±75
±750
±38
±375
±0.08 ±0.75
±0.5
±2.8
0.5
100
±10
±32
90
±50
TYP
±0.3
±2
2
100
±10
86
OPA2111KM, KP
MAX
MIN
+125
0
±1.5
±6
82
±50
±2nA ±16.3nA
1nA
±1.3nA ±12nA
TYP
MAX
UNITS
+70
°C
±5
±15
mV
µV/°C
µV/°C
dB
µV/V
±0.9
±8
2
100
±10
±80
±125
±500
pA
pA
±75
±375
pA
VIN = ±10VDC
±10
86
±11
100
±10
90
±11
100
±10
86
±11
100
±10
80
±11
100
V
dB
RL ≥ 2kΩ
106
120
5
110
120
3
106
120
5
100
120
5
dB
dB
RL = 2kΩ
VO = ±10VDC
VO = 0VDC
±10.5
±5
10
±11
±10
40
±10.5
±5
10
±11
±10
40
±10.5
±5
10
±11
±10
40
±10.5
±5
10
±11
±10
40
V
mA
mA
OPEN-LOOP GAIN, DC
Open-Loop Voltage Gain
Match
RATED OUTPUT
Voltage Output
Current Output
Short Circuit Current
MIN
±1.2
±6
86
OFFSET CURRENT(1)
Input Offset Current
OPA2111BM
MAX
±0.22
±2
1
100
±10
VCM = 0VDC
BIAS CURRENT(1)
Input Bias Current
Match
TYP
POWER SUPPLY
Current, Quiescent
IO = 0mADC
5
8
5
8
5
8
5
10
mA
NOTES: (1) Offset voltage, offset current, and bias current are measured with the units fully warmed up.
ABSOLUTE MAXIMUM RATINGS
CONNECTION DIAGRAMS
Top View
Supply ........................................................................................... ±18VDC
Internal Power Dissipation (TJ ≤ +175°C) .................................... 500mW
Differential Input Voltage ............................................................ Total VCC
Input Voltage Range .......................................................................... ±VCC
Storage Temperature Range: “M” Package .................. –65°C to +150°C
“P” Package .................... –40°C to +85°C
Operating Temperature Range: “M” Package ............... –55°C to +125°C
“P” Package ................. –40°C to +85°C
Lead Temperature (soldering, 10s) ............................................... +300°C
Output Short Circuit to Ground (+25°C) ................................. Continuous
Junction Temperature .................................................................... +175°C
DIP
Out A
1
–In A
2
+In A
3
–VCC
4
A
B
8
+VCC
7
Out B
6
–In B
5
+In B
PACKAGE INFORMATION
MODEL
Top View
OPA2111AM
OPA2111BM
OPA2111KM
OPA2111SM
OPA2111KP
TO-99
+VCC and Case
8
Out A 1
7 Out B
A
+In A
6 –In B
TO-99
TO-99
TO-99
TO-99
8-Pin Plastic DIP
001
001
001
001
006
ORDERING INFORMATION
5 +In B
3
PACKAGE DRAWING
NUMBER(1)
NOTE: (1) For detailed drawing and dimension table, please see end of data
sheet, or Appendix D of Burr-Brown IC Data Book.
B
–In A 2
PACKAGE
TEMPERATURE
OFFSET
VOLTAGE,
RANGE
max (mV)
1–24
±0.75
±0.5
±2
±0.75
±2
$12.50
21.60
25.55
4
–VCC
MODEL
OPA2111AM
OPA2111BM
OPA2111KM
OPA2111SM
OPA2111KP
PACKAGE
TO-99
–25°C to +85°C
TO-99
–25°C to +85°C
TO-99
0°C to +70°C
TO-99
–55°C to +125°C
8-Pin Plastic DIP
0°C to +70°C
®
3
OPA2111
DICE INFORMATION
PAD
FUNCTION
1
2
3
4
5
6
7
8
NC
Out A
–In A
+In A
–VS
+In B
–In B
Out B
+VS
No Connection
Substrate Bias: No Connection
MECHANICAL INFORMATION
Die Size
Die Thickness
Min. Pad Size
OPA2111AD DIE TOPOGRAPHY
MILS (0.001")
MILLIMETERS
138 x 84 ±5
20 ±3
4x4
3.51 x 2.13 ±0.13
0.51 ±0.08
0.10 x 0.10
Backing
Transistor Count
None
102
TYPICAL PERFORMANCE CURVES
TA = +25°C, and VCC = ±15VDC unless otherwise noted.
VOLTAGE AND CURRENT NOISE SPECTRAL
DENSITY vs TEMPERATURE
INPUT CURRENT NOISE SPECTRAL DENSITY
100
100
12
10
1
BM
10
10
8
1
6
0.1
4
0.1
1
10
100
1k
10k
100k
–75
1M
Frequency (Hz)
–25
0
25
50
Temperature (°C)
®
OPA2111
–50
4
75
100
0.01
125
Current Noise (fA/ Hz)
Voltage Noise (nV/ Hz)
Current Noise (fA/ Hz)
fO = 1kHz
TYPICAL PERFORMANCE CURVES
(CONT)
TA = +25°C, and VCC = ±15VDC unless otherwise noted.
TOTAL(1) INPUT VOLTAGE NOISE SPECTRAL
DENSITY vs SOURCE RESISTANCE
INPUT OFFSET VOLTAGE WARM-UP DRIFT
1k
40
Offset Voltage Change (µV)
RS = 1MΩ
100
RS = 100kΩ
BM
10
RS = 100Ω
NOTE: (1) Includes contribution
from source resistance.
1
1
10
100
1k
10k
–20
0
100k
1
2
3
4
5
Frequency (Hz)
Time From Power Turn-On (Minutes)
INPUT VOLTAGE NOISE SPECTRAL DENSITY
BIAS AND OFFSET CURRENT
vs TEMPERATURE
1k
Bias Current (pA)
1k
Voltage Noise (nV/ Hz)
0
–40
0.1
100
AM, SM
BM
10
100
100
10
10
1
1
0.1
0.01
1
10
100
1k
10k
100k
6
1k
0.1
1
0.01
–50
1M
–25
0
25
50
75
Frequency (Hz)
Ambient Temperature (°C)
TOTAL(1) INPUT VOLTAGE NOISE (PEAK-TO-PEAK)
vs SOURCE RESISTANCE
POWER SUPPLY REJECTION
vs FREQUENCY
100
125
1M
10M
140
Power Supply Rejection (dB)
1k
Voltage Noise (µVp-p)
20
Offset Current (pA)
Voltage Noise (nV/ Hz)
RS = 10MΩ
NOTE: (1) Includes contribution
from source resistance.
100
BM
fB = 0.1Hz to 10Hz
10
120
100
80
60
40
20
0
1
10
4
10 5
10
6
10
7
10
8
10
9
10
10
1
Source Resistance (Ω)
10
100
1k
10k
100k
Frequency (Hz)
®
5
OPA2111
TYPICAL PERFORMANCE CURVES
(CONT)
TA = +25°C, and VCC = ±15VDC unless otherwise noted.
COMMON-MODE REJECTION
vs INPUT COMMON-MODE VOLTAGE
TOTAL INPUT VOLTAGE NOISE SPECTRAL DENSITY
AT 1kHz vs SOURCE RESISTANCE
120
EO
RS
100
Common-Mode Rejection (dB)
Voltage Noise, EO (nV/ Hz)
1k
BM
OPA2111 +
Resistor
10
Resistor Noise Only
110
100
90
80
70
1
100
1k
10k
100k
1M
10M
–15
100M
–5
5
10
INPUT OFFSET VOLTAGE CHANGE
DUE TO THERMAL SHOCK
GAIN-BANDWIDTH AND SLEW RATE
vs TEMPERATURE
15
4
4
3
3
2
2
1
1
BM
0
25°C
85°C
TA = 25°C to TA = 85°C
Air Environment
–75
0
0
–1
0
1
2
3
4
5
–75
–50
–25
Time From Thermal Shock (Minutes)
0
25
50
75
100
125
100
125
Ambient Temperature (°C)
BIAS AND OFFSET CURRENT
vs INPUT COMMON-MODE VOLTAGE
OPEN-LOOP GAIN vs TEMPERATURE
10
1
Offset Current
0.1
0.1
130
Voltage Gain (dB)
Bias Current
1
140
Offset Current (pA)
10
120
110
0.01
0.01
–15
–10
–5
0
5
10
100
15
–75
®
OPA2111
–50
–25
0
25
50
Ambient Temperature (°C)
Common-Mode Voltage (V)
6
75
Slew Rate (V/µs)
Gain Bandwidth (MHz)
AM
75
–150
Bias Current (pA)
0
Common-Mode Voltage (V)
150
Offset Voltage Change (µV)
–10
Source Resistance (Ω)
TYPICAL PERFORMANCE CURVES
(CONT)
TA = +25°C, VCC = ±15VDC unless otherwise noted.
COMMON-MODE REJECTION
vs FREQUENCY
LARGE SIGNAL TRANSIENT RESPONSE
120
15
100
Output Voltage (V)
Common-Mode Rejection (dB)
140
80
60
40
0
–15
20
0
1
10
100
1k
10k
100k
1M
25
0
10M
OPEN-LOOP FREQUENCY RESPONSE
SETTLING TIME vs CLOSED-LOOP GAIN
140
100
Gain
φ
80
–90
Phase
Margin
≈ 65°
60
40
–135
80
Settling Time (µs)
100
Phase Shift (Degrees)
–45
60
0.01%
40
0.1%
20
20
0
–180
1
10
100
1k
10k
100k
1M
0
1
10M
10
GAIN-BANDWIDTH AND SLEW RATE
vs SUPPLY VOLTAGE
CHANNEL SEPARATION vs FREQUENCY
1
1
0
Channel Separation (dB)
2
2
10
15
RL = ∞
140
RL = 2kΩ
130
RL = 560Ω
120
110
100
0
5
1k
150
3
3
0
100
Closed-Loop Gain (V/V)
Frequency (Hz)
Slew Rate (V/µs)
Voltage Gain (dB)
120
Gain Bandwidth (MHz)
50
Time (µs)
Frequency (Hz)
10
20
Supply Voltage (±VCC )
100
1k
10k
100k
Frequency (Hz)
®
7
OPA2111
TYPICAL PERFORMANCE CURVES
(CONT)
TA = +25°C, VCC = ±15VDC unless otherwise noted.
MAXIMUM UNDISTORTED OUTPUT
VOLTAGE vs FREQUENCY
SUPPLY CURRENT vs TEMPERATURE
8
Supply Current (mA)
Output Voltage (Vp-p)
30
20
10
0
6
4
2
0
1k
10k
100k
1M
–75
–50
–25
0
25
50
75
Frequency (Hz)
Ambient Temperature (°C)
SMALL SIGNAL TRANSIENT RESPONSE
TOTAL HARMONIC DISTORTION
vs FREQUENCY
100
125
1
60
Total Harmonic Distortion (%)
10kΩ
Output Voltage (mV)
40
20
0
–20
–40
10kΩ
EO = 7V
EO
0.1
2kΩ
EO =
700mV
0.01
THD + Noise
Residual Test Limit
0.001
–60
0
1
2
3
4
5
0.1
1
10
100
1K
10K
100K
Frequency (Hz)
Time (µs)
APPLICATIONS INFORMATION
OFFSET VOLTAGE ADJUSTMENT
INPUT PROTECTION
The OPA2111 offset voltage is laser-trimmed and will
require no further trim for most applications.
Conventional monolithic FET operational amplifiers require
external current-limiting resistors to protect their inputs
against destructive currents that can flow when input FET
gate-to-substrate isolation diodes are forward-biased. Most
BIFET amplifiers can be destroyed by the loss of –VCC.
Offset voltage can be trimmed by summing (see Figure 1).
With this trim method there will be no degradation of input
offset drift.
In
Because of its dielectric isolation, no special protection is
needed on the OPA2111. Of course, the differential and
common-mode voltage limits should be observed. Static
damage can cause subtle changes in amplifier input characteristics without necessarily destroying the device. In precision operational amplifiers (both bipolar and FET types),
this may cause a noticeable degradation of offset voltage and
drift.
1/2 OPA2111
Out
150kΩ
–15V
±2mV
OffsetTrim
100kΩ
20Ω
Static protection is recommended when handling any precision IC operational amplifier.
+15V
FIGURE 1. Offset Voltage Trim.
®
OPA2111
8
GUARDING AND SHIELDING
APPLICATIONS CIRCUITS
As in any situation where high impedances are involved,
careful shielding is required to reduce “hum” pickup in input
leads. If large feedback resistors are used, they should also
be shielded along with the external input circuitry.
Figures 5 through 13 are circuit diagrams of various applications for the OPA2111.
Leakage currents across printed circuit boards can easily
exceed the bias current of the OPA2111. To avoid leakage
problems, it is recommended that the signal input lead of the
OPA2111 be wired to a Teflon standoff. If the OPA2111 is
to be soldered directly into a printed circuit board, utmost
care must be used in planning the board layout. A “guard”
pattern should completely surround the high impedance
input leads and should be connected to a low impedance
point which is at the signal input potential (see Figure 2).
Voltage Noise Spectral Density (EO)
Typical at 1kHz (nV/ Hz)
1k
NOISE: FET vs BIPOLAR
RS
100
EO = eN2 + (iNRS)2 + 4kTRS
10
OPA2111 + Resistor
Resistor Noise Only
OP-27 + Resistor
1
100
Low noise circuit design requires careful analysis of all
noise sources. External noise sources can dominate in many
cases, so consider the effect of source resistance on overall
operational amplifier noise performance. At low source
impedances, the low voltage noise of a bipolar operational
amplifier is superior, but at higher impedances the high
current noise of a bipolar amplifier becomes a serious
liability. Above about 15kΩ the OPA2111 will have lower
total noise than an OP-27 (see Figure 3).
OP-27 + Resistor
OPA2111 + Resistor
Resistor Noise Only
EO
1k
10k
BM
100k
1M
10M
Source Resistance, RS (Ω)
FIGURE 3. Voltage Noise Spectral Density vs Source
Resistance.
Input Bias Current (pA)
80
BIAS CURRENT CHANGE
vs COMMON-MODE VOLTAGE
The input bias currents of most popular BIFET® operational amplifiers are affected by common-mode voltage
(Figure 4). Higher input FET gate-to-drain voltage causes
leakage and ionization (bias) currents to increase. Due to its
cascode input stage, the extremely low bias current of the
OPA2111 is not compromised by common-mode voltage.
TA = 25°C; curves taken from
manufacturers' published
typical data
60
LF156/157
40
20
0
LF155
AD547
OPA2111
OP-15/16/17 “Perfect Bias Current Cancellation”
–20
–15
–10
–5
0
5
10
15
Common-Mode Voltage (VDC)
Non-Inverting
Buffer
2
2
A
In
FIGURE 4. Input Bias Currrent vs Common-Mode Voltage.
1
Out
3
Out
1
A
1MΩ
In Operate 10kΩ
3
In
1/2
OPA2111BM
Zero
Inverting
2
Out
1
3
TO-99 Bottom View
100kΩ
4
In
2
A
1
Gain = –100
3
Out
5
2
100Ω
6
100kΩ
VOS ≤ 5µV
Drift ≤ 0.028µV/°C
Zero Droop ≤ 2µV/s
Referred to Input
Polypropylene
1µF
3
7
1
6
8
7
Board layout for input guarding: guard top and bottom of board.
Alternate: use Teflon® standoff for sensitive input pins.
1/2
OPA2111BM
5
Teflon® E. I. Du Pont de Nemours & Co.
FIGURE 2. Connection of Input Guard.
FIGURE 5. Auto-Zero Amplifier.
®
9
OPA2111
<1pF to prevent gain peaking
100Ω
1000MΩ
10kΩ
2
1/2 OPA2111BM
1
+15V
Pin Photodiode
UDT Pin-040A
3
5.34MΩ(1)
Guard
0.1µF
2
8
1/2 OPA2111
3
0.01µF
5
1000pF
7
4 0.1µF
1000MΩ
1/2 OPA2111BM
In
Output
1
Out
5.34MΩ(1)
5 x 108V/W
2.67MΩ(1)
500pF
–15V
Circuit must be well shielded.
2kΩ
Q
6
500pF
NOTE: (1) For 50Hz use 3.16MΩ and 6.37Ω.
Gain = 101
FIGURE 6. Sensitive Photodiode Amplifier.
FIGURE 7. High Impedance 60Hz Reject Filter with Gain.
10.5kΩ 0.03µF
0.01µF
73.2Ω
365Ω
Right
2
1/2 OPA2111
1
365kΩ
1µF
Output
3
L
Input
0.01µF
RT
100kΩ
CT
10.5kΩ 0.03µF
0.01µF
73.2Ω
365Ω
Left
6
1/2 OPA2111
7
365Ω
1µF
Output
5
R
Input
100kΩ
RT
0.01µF
CT
G = 26dB Midband
FIGURE 8. RIAA Equalized Stereo Preamplifier.
®
OPA2111
10
3
IB = ±4pA max
Gain = 100
CMRR ≈ 106dB
RIN ≈ 1013Ω
1/2 OPA2111BM
1
–In
2
RF
5kΩ
RG
101Ω
6
25kΩ
2
RF
5kΩ
25kΩ
5
6
25kΩ
3
Output
1/2 OPA2111BM
25kΩ
7
5
Burr-Brown
INA105
Differential
Amplifier
1
+In
Differential Voltage Gain = 1 + 2RF /RG
FIGURE 9. FET Input Instrumentation Amplifier.
10kΩ
≈10pF
(1)
1MΩ
6
IN914
2
1/2
OPA2111AM
1/2
OPA2111AM
(1)
1
3
Output
7
(1)
IN914
Input
5
Droop ≈ 0.5mV/s
2N4117A
0.01µF
Polystyrene
NOTE: (1) Reverse polarity for
negative peak detection.
FIGURE 10. Low-Droop Positive Peak Detector.
6.3MΩ
944kΩ
6.3MΩ
2
1.6MΩ
1.6MΩ
1/2 OPA2111
6
1.6MΩ
1
1.6MΩ
3
7.8MΩ
1/2 OPA2111
5
7
Out
In
0.01µF
NPO
0.01µF
NPO
0.01µF
NPO
NOTE: Lower value resistors will have lower
thermal noise but capacitors must
be scaled larger.
0.01µF
NPO
AV = 2.6
fO = 10Hz
–24dB/Octave
FIGURE 11. 10Hz Fourth-Order Butterworth Low-Pass Filter.
®
11
OPA2111
100Ω
10kΩ
2
Input
1/2OPA2111
1
10kΩ
3
100Ω
10kΩ
Since signal voltage sums directly with N
but amplifier noise voltage sums as N,
signal-to-noise ratio improves by N.
6
1/2OPA2111
7
10kΩ
5
100Ω
AV = –1010
en = 1.9nV/ Hz typ(1) at 10kHz
BW = 30kHz typ
GBW = 30.3 MHz typ
VOS = ±16µV typ(1)
∆VOS/∆T = ±0.16µV/°C typ(1)
IB = 40pA max
ZIN = 1012Ω || 30pF
10kΩ
2
1/2OPA2111
1
10kΩ
3
100Ω
10kΩ
6
1/2OPA2111
7
NOTE: (1) Theoretical performance
achievable from OPA2111BM
with uncorrelated random
distribution of parameters.
10kΩ
5
100Ω
10kΩ
2
1/2OPA2111
1
10kΩ
10kΩ
3
2
3
1/2OPA2111
N = 10
5 each OPA2111BM
FIGURE 12. ‘N’ Stage Parallel-Input Amplifier.
®
OPA2111
12
Output
OPA37
6
1/2 OPA2111
E1
–In
1
A1
R2
10kΩ
R1
202Ω
R2
10kΩ
10kΩ
2
INA106
100kΩ
6
10kΩ
3
5
EO
Output
1/2 OPA2111
100kΩ
AV = 10
A2
1
E2
+In
EO = 10(1 + 2 R2/R1)(E2 – E1) = 1000(E2 – E1)
Using the INA106 for an output difference amplifier extends the input common-mode
range of an instrumentation amplifier to ±10V. A conventional IA with a unity-gain difference
amplifier has an input common-mode range limited to ±5V for an output swing of ±10V. This
is because a unity-gain difference amp needs ±5V at the input for 10V at the output,
allowing only 5V additional for common-mode.
FIGURE 13. Precision Instrumentation Amplifier.
The information provided herein is believed to be reliable; however, BURR-BROWN assumes no responsibility for inaccuracies or omissions. BURR-BROWN assumes
no responsibility for the use of this information, and all use of such information shall be entirely at the user’s own risk. Prices and specifications are subject to change
without notice. No patent rights or licenses to any of the circuits described herein are implied or granted to any third party. BURR-BROWN does not authorize or warrant
any BURR-BROWN product for use in life support devices and/or systems.
®
13
OPA2111