OP297_03 [ADI]
Dual Low Bias Current Precision Operational Amplifier; 双通道，低偏置电流精密运算放大器
| 型号： | OP297_03 |
| 厂家： | 
ADI |
| 描述： | Dual Low Bias Current Precision Operational Amplifier |
| 文件： | 总12页 (文件大小：267K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Dual Low Bias Current
Precision Operational Amplifier
OP297
FEATURES
PIN CONNECTIONS
Low Offset Voltage: 50 V Max
Low Offset Voltage Drift: 0.6 V/؇C Max
Very Low Bias Current: 100 pA Max
1
2
3
4
8
7
6
5
V+
OUTA
–INA
+INA
V–
OUTB
–INB
+INB
A
B
Very High Open-Loop Gain: 2000 V/mV Min
Low Supply Current (Per Amplifier): 625 A Max
Operates From ؎2 V to ؎20 V Supplies
High Common-Mode Rejection: 120 dB Min
Pin Compatible to LT1013, AD706, AD708, OP221,
LM158, and MC1458/1558 with Improved Performance
Precision performance of the OP297 includes very low offset,
under 50 µV, and low drift, below 0.6 µV/°C. Open-loop gain
exceeds 2000 V/mV, ensuring high linearity in every application.
APPLICATIONS
Strain Gage and Bridge Amplifiers
High Stability Thermocouple Amplifiers
Instrumentation Amplifiers
Photo-Current Monitors
High Gain Linearity Amplifiers
Long-Term Integrators/Filters
Sample-and-Hold Amplifiers
Peak Detectors
Errors due to common-mode signals are eliminated by the
OP297’s common-mode rejection of over 120 dB, which mini-
mizes offset voltage changes experienced in battery-powered
systems. Supply current of the OP297 is under 625 µA per
amplifier, and the part can operate with supply voltages as low
as 2 V.
Logarithmic Amplifiers
Battery-Powered Systems
The OP297 uses a super-beta input stage with bias current
cancellation to maintain picoamp bias currents at all temperatures.
This is in contrast to FET input op amps whose bias currents
start in the picoamp range at 25°C, but double for every 10°C
rise in temperature, to reach the nanoamp range above 85°C.
Input bias current of the OP297 is under 100 pA at 25°C and is
under 450 pA over the military temperature range.
GENERAL DESCRIPTION
The OP297 is the first dual op amp to pack precision performance
into the space-saving, industry-standard, 8-lead SOIC package.
Its combination of precision with low power and extremely low
input bias current makes the dual OP297 useful in a wide variety
of applications.
Combining precision, low power, and low bias current, the OP297
is ideal for a number of applications, including instrumentation
amplifiers, log amplifiers, photodiode preamplifiers, and long-
term integrators. For a single device, see the OP97; for a quad,
see the OP497.
60
V
V
= ؎15V
S
400
= 0V
CM
1200 UNITS
T
= 25؇C
A
40
20
0
V
= ؎15V
= 0V
S
V
CM
300
200
100
0
I –
B
I +
B
–20
–40
–60
I
OS
–75
–50
–25
0
25
50
75
100
125
TEMPERATURE (؇C)
–100 –80 –60 –40
–20
0
20
40
60
80 100
INPUT OFFSET VOLTAGE (V)
Figure 1. Low Bias Current over Temperature
REV. E
Figure 2. Very Low Offset
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, norforanyinfringementsofpatentsorotherrightsofthirdpartiesthat
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective companies.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
Fax: 781/326-8703
www.analog.com
© 2003 Analog Devices, Inc. All rights reserved.
OP297–SPECIFICATIONS
ELECTRICAL CHARACTERISTICS
(@ VS = ؎15 V, TA = 25؇C, unless otherwise noted.)
OP297E
Min Typ
OP297F
Typ Max Min
OP297G
Typ Max Unit
Parameter
Symbol Conditions
Max Min
Input Offset Voltage
Long-Term Input
VOS
25
50
50
100
80
200
µV
Voltage Stability
0.1
20
20
0.5
20
17
20
0.1
35
35
0.5
20
17
20
0.1
50
50
0.5
20
17
20
µV/mo
Input Offset Current
Input Bias Current
Input Noise Voltage
Input Noise Voltage Density
IOS
IB
en p-p
en
VCM = 0 V
VCM = 0 V
0.1 Hz to 10 Hz
fO = 10 Hz
fO = 1000 Hz
fO = 10 Hz
100
100
150
150
200
pA
200 pA
µV p-p
nV/√Hz
nV/√Hz
fA/√Hz
Input Noise Current Density
Input Resistance
in
Differential Mode
Input Resistance
Common-Mode
RIN
RINCM
30
500
30
30
500
MΩ
GΩ
500
Large-Signal
VO
= 10 V
Voltage Gain
AVO
VCM
CMRR VCM
PSRR
VO
RL = 2 kΩ
2000 4000
1500 3200
1200 3200
V/mV
V
dB
dB
V
V
µA
V
Input Voltage Range*
Common-Mode Rejection
Power Supply Rejection
Output Voltage Swing
13
120
14
140
130
14
13.7
525
13
114
114
13
14
135
125
14
13
114
114
13
14
135
125
14
=
13 V
VS = 2 V to 20 V 120
RL = 10 kΩ
13
13
RL = 2 kΩ
13
13.7
13
13.7
Supply Current per Amplifier
Supply Voltage
ISY
VS
No Load
625
20
525 625
20
525 625
20
Operating Range
2
2
2
Slew Rate
Gain Bandwidth Product
Channel Separation
SR
0.05 0.15
500
0.05
0.15
500
150
0.05
0.15
500
150
V/µs
kHz
dB
GBWP AV = +1
CS
VO = 20 V p-p
fO = 10 Hz
150
Input Capacitance
CIN
3
3
3
pF
*Guaranteed by CMR test.
Specifications subject to change without notice.
(@ VS = ؎15 V, –40؇C Յ TA Յ +85؇C for OP297E/F/G, unless otherwise noted.)
ELECTRICAL CHARACTERISTICS
OP297E
Min Typ
OP297F
Max Min Typ
OP297G
Max Min Typ Max Unit
Parameter
Symbol Conditions
Input Offset Voltage
Average Input Offset
Voltage Drift
Input Offset Current
Input Bias Current
Large-Signal Voltage Gain
VOS
35
100
80
300
110
400
µV
TCVOS
IOS
IB
0.2
50
50
0.6
450
450
0.5
80
80
2.0
750
750
0.6
80
80
2.0
750
750 pA
µV/°C
pA
VCM = 0 V
VCM = 0 V
AVO
VO
= 10 V,
RL = 2 kΩ
1200 3200
1000 2500
800 2500
V/mV
V
dB
Input Voltage Range*
Common-Mode Rejection
Power Supply Rejection
VCM
13
114
13.5
130
13
108
13.5
130
13
13.5
CMRR VCM
=
13
108 130
PSRR
VS = 2.5 V
to 20 V
RL = 10 kΩ
No Load
114
13
0.15
13.4
550
108
13
0.15
13.4
550
108 0.3
dB
V
µA
V
Output Voltage Swing
Supply Current per Amplifier ISY
Supply Voltage
VO
13
13.4
550
750
20
750
20
750
20
VS
Operating Range
2.5
2.5
2.5
*Guaranteed by CMR test.
Specifications subject to change without notice.
–2–
REV. E
OP297
ABSOLUTE MAXIMUM RATINGS1
3
Package Types
Unit
JA
JC
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 V
Input Voltage2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 V
Differential Input Voltage2 . . . . . . . . . . . . . . . . . . . . . . . . 40 V
Output Short-Circuit Duration . . . . . . . . . . . . . . . . . Indefinite
Storage Temperature Range
8-Lead CERDIP (Z)
8-Lead PDIP (P)
8-Lead SOIC (S)
134
96
150
12
37
41
°C/W
°C/W
°C/W
NOTES
1 Stresses above those listed under Absolute Maximum Ratings may cause perma-
nent damage to the device. This is a stress rating only; and functional operation
of the device at these or any other conditions above those indicated in the
operational section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
2 For supply voltages less than 20 V, the absolute maximum input voltage is equal
to the supply voltage.
Z Package . . . . . . . . . . . . . . . . . . . . . . . . . –65°C to +175°C
P, S Packages . . . . . . . . . . . . . . . . . . . . . . –65°C to +150°C
Operating Temperature Range
OP297E (Z) . . . . . . . . . . . . . . . . . . . . . . . . –40°C to +85°C
OP297F, OP297G (P, S) . . . . . . . . . . . . . . –40°C to +85°C
Junction Temperature
Z Package . . . . . . . . . . . . . . . . . . . . . . . . . –65°C to +175°C
P, S Packages . . . . . . . . . . . . . . . . . . . . . . –65°C to +150°C
Lead Temperature Range (Soldering, 60 sec) . . . . . . . . 300°C
3 ꢀJA is specified for worst case mounting conditions, i.e., ꢀJA is specified for device
in socket for CERDIP and PDIP, packages; ꢀJA is specified for device soldered to
printed circuit board for SOIC package.
ORDERING GUIDE
Model
Temperature Range
Package Description
Package Options
OP297EZ
OP297FP
OP297FS
OP297FS-REEL
OP297FS-REEL7
OP297GP
OP297GS
OP297GS-REEL
OP297GS-REEL7
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
8-Lead CERDIP
8-Lead PDIP
8-Lead SOIC
8-Lead SOIC
8-Lead SOIC
8-Lead PDIP
8-Lead SOIC
8-Lead SOIC
8-Lead SOIC
Q-8
N-8
R-8
R-8
R-8
N-8
R-8
R-8
R-8
CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection. Although the
OP297 features proprietary ESD protection circuitry, permanent damage may occur on devices
subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended
to avoid performance degradation or loss of functionality.
1/2
OP297
V
2k⍀
20Vp-p @ 10Hz
1
50k⍀
50⍀
1/2
OP297
V
2
V
1
CHANNEL SEPARATION = 20 log
)
)
V /10000
2
Figure 3. Channel Separation Test Circuit
REV. E
–3–
OP297–Typical Performance Characteristics
400
300
200
100
250
200
150
400
T
V
V
= 25؇C
= ؎15V
= 0V
T
V
V
= 25؇C
= ؎15V
= 0V
T
V
V
= 25؇C
= ؎15V
= 0V
1200 UNITS
1200 UNITS
A
A
1200 UNITS
A
S
S
S
CM
CM
CM
300
200
100
0
100
50
0
0
–100 –80 –60 –40 –20
0
20 40 60 80 100
–100 –80 –60 –40 –20
0
20 40 60 80 100
–100 –80 –60 –40 –20
0
20 40 60 80 100
INPUT OFFSET VOLTAGE (pA)
INPUT BIAS CURRENT (pA)
INPUT OFFSET VOLTAGE (pA)
TPC 1. Typical Distribution of
Input Offset Voltage
TPC 2. Typical Distribution of
Input Bias Current
TPC 3. Typical Distribution of
Input Offset Current
60
40
60
؎3
؎2
؎1
0
V
V
= ؎15V
V
V
= ؎15V
S
T
V
V
= 25؇C
= ؎15V
S
A
= 0V
= 0V
CM
CM
S
= 0V
CM
I
–
40
20
B
20
I
+
B
I
–
B
0
I
+
B
0
–20
–40
–60
I
OS
I
OS
–20
–40
–75 –50 –25
0
25
50 75 100 125
–10
–5
0
5
10
15
–15
0
1
2
3
4
5
TEMPERATURE (؇C)
COMMON-MODE VOLTAGE (V)
TIME AFTER POWER APPLIED (Minutes)
TPC 4. Input Bias, Offset
Current vs. Temperature
TPC 5. Input Bias, Offset Current vs.
Common-Mode Voltage
TPC 6. Input Offset Voltage
Warm-Up Drift
100
35
10000
1000
BALANCED OR UNBALANCED
T
T
= –55؇C
= +25؇C
A
30
25
BALANCED OR UNBALANCED
V
V
= ؎15V
S
V
V
= ؎15V
= 0V
S
CM
20
15
10
5
= 0V
A
CM
10
1
T
= +125؇C
A
V
= ؎15V
S
0
OUTPUT SHORTED
TO GROUND
–5
–10
–15
–20
–25
–30
–35
100
10
T
= +125؇C
= +25؇C
A
–55؇C
T
+125؇C
A
T
A
A
T
= –55؇C
T
= +25؇C
A
0.1
100
0
1
2
3
4
1k
10k
100k
1M
10M 100M
10
100
1k
10k
100k
1M
10M
TIME FROM OUTPUT SHORT (Minutes)
SOURCE RESISTANCE (⍀)
SOURCE RESISTANCE (⍀)
TPC 7. Effective Offset Voltage
vs. Source Resistance
TPC 8. Effective TCVOS vs.
Source Resistance
TPC 9. Short Circuit Current
vs. Time, Temperature
–4–
REV. E
OP297
1300
160
140
120
100
160
140
120
100
80
NO LOAD
T
V
= 25؇C
= ؎15V
A
T
= 25؇C
A
S
V
= ؎15V
S
T
= +125؇C
= +25؇C
A
1200
1100
⌬V = 10Vp-p
S
T
A
1000
900
80
60
40
T
= –55؇C
A
60
40
800
0
1
10
100
1k
10k
100k
1M
0.1
1
10
100
1k
10k 100k 1M
؎5
؎10
؎15
؎20
SUPPLY VOLTAGE (V)
FREQUENCY (Hz)
FREQUENCY (Hz)
TPC 10. Total Supply Current
vs. Supply Voltage
TPC 11. Common-Mode Rejection
Frequency
TPC 12. Power Supply Rejection vs.
Frequency
10
10000
1000
100
1000
100
T
V
= 25؇C
= ؎2V TO ؎20V
T
V
= 25؇C
= ؎2V TO ؎15V
A
A
T
= –55؇C
A
S
S
T
= +25؇C
A
1
T
= +125؇C
A
10Hz
CURRENT
NOISE
1000
1kHz
VOLTAGE
NOISE
10
1
10
0.1
V
= ؎15V
= ؎10V
1kHz
10Hz
S
V
O
0.01
100
1
1000
2
3
4
5
6
7
10
1
3
4
5
10
20
2
1
10
100
10
10
SOURCE RESISTANCE (⍀)
10
10
10
FREQUENCY (Hz)
LOAD RESISTANCE (k⍀)
TPC 13. Voltage Noise Density and
Current Noise Density vs. Frequency
TPC 14. Total Noise Density
vs. Source Resistance
TPC 15. Open-Loop Gain vs.
Load Resistance
35
35
T
V
A
= 25؇C
= ؎15V
A
T
V
A
= 25؇C
= ؎15V
= +1
R
V
= 10k⍀
= ؎15V
= 0V
A
L
S
30
25
20
30
25
20
S
S
= +1
VCL
V
VCL
CM
1%THD
T
= +125؇C
A
1%THD
= 1kHz
f
= 1kHz
= 10k⍀
O
f
O
R
L
T
= +25؇C
= –55؇C
A
15
10
5
15
10
5
0
T
A
0
0
100
10
100
1k
10k
1k
10k
100k
–15
–10
–5
0
5
10
15
OUTPUT VOLTAGE (V)
LOAD RESISTANCE (⍀)
FREQUENCY (Hz)
TPC 16. Differential Input
Voltage vs. Output Voltage
TPC 17. Output Swing vs. Load
Resistance
TPC 18. Maximum Output
Swing vs. Frequency
REV. E
–5–
OP297
70
60
50
40
30
20
100
1000
100
10
T
V
= 25؇C
= ؎15V
T
V
A
V
= 25؇C
= ؎15V
A
A
V
C
R
= ؎15V
= 30pF
= 1M⍀
S
80
S
S
L
L
GAIN
–EDGE
= +1
VCL
60
40
20
0
= 100mV p-p
OUT
PHASE
T
= –55؇C
A
+EDGE
1
0.1
0.01
–20
–40
10
0
T
= +125؇C
A
0.001
10
100
1k
10k
100k
1M
100
100
FREQUENCY (Hz)
1M
10M
0
1k
10k
100
1000
10000
FREQUENCY (Hz)
LOAD CAPACITANCE (pF)
TPC 19. Open Loop Gain, Phase
vs. Frequency
TPC 20. Small-Signal Over-
shoot vs. Load Capacitance
TPC 21. Open Loop Output
Impedance vs Frequency
APPLICATIONS INFORMATION
Extremely low bias current over a wide temperature range makes
the OP297 attractive for use in sample-and-hold amplifiers,
peak detectors, and log amplifiers that must operate over a wide
temperature range. Balancing input resistances is unnecessary
with the OP297. Offset voltage and TCVOS are degraded only
minimally by high source resistance, even when unbalanced.
100
90
The input pins of the OP297 are protected against large differ-
ential voltage by back-to-back diodes and current-limiting
resistors. Common-mode voltages at the inputs are not restricted
and may vary over the full range of the supply voltages used.
10
0%
20mV
5s
The OP297 requires very little operating headroom about the
supply rails and is specified for operation with supplies as low as
2 V. Typically, the common-mode range extends to within 1 V
of either rail. The output typically swings to within 1 V of the
rails when using a 10 kΩ load.
Figure 5. Small-Signal Transient Response
(CLOAD = 1000 pF, AVCL = 1)
AC PERFORMANCE
100
90
The OP297’s ac characteristics are highly stable over its full
operating temperature range. Unity gain small-signal response is
shown in Figure 4. Extremely tolerant of capacitive loading on
the output, the OP297 displays excellent response with 1000 pF
loads (Figure 5).
10
0%
20mV
5s
100
90
Figure 6. Large-Signal Transient Response
(AVCL = 1)
10
0%
20mV
5s
Figure 4. Small-Signal Transient Response
(CLOAD = 100 pF, AVCL = 1)
–6–
REV. E
OP297
UNITY-GAIN FOLLOWER
NONINVERTING AMPLIFIER
APPLICATIONS
PRECISION ABSOLUTE VALUE AMPLIFIER
The circuit of Figure 9 is a precision absolute value amplifier with
an input impedance of 30 MΩ. The high gain and low TCVOS
of the OP297 ensure accurate operation with microvolt input
signals. In this circuit, the input always appears as a common-
mode signal to the op amps. The CMR of the OP297 exceeds
120 dB, yielding an error of less than 2 ppm.
1/2
OP297
1/2
OP297
+15V
C2
0.1F
MINI-DIP
BOTTOM VIEW
INVERTING AMPLIFIER
R1
1k⍀
R3
1k⍀
8
1
C1
30pF
5
D 1
1N4148
A
1/2
OP297
7
2
3
8
1/2
OP297
B
1/2
1
6
0V
V
10V
OUT
OP297
D 2
1N4148
V
IN
C3
R2
0.1F
2k⍀
4
–15V
Figure 7. Guard Ring Layout and Connections
Figure 9. Precision Absolute Value Amplifier
GUARDING AND SHIELDING
To maintain the extremely high input impedances of the OP297,
care must be taken in circuit board layout and manufacturing.
Board surfaces must be kept scrupulously clean and free of mois-
ture. Conformal coating is recommended to provide a humidity
barrier. Even a clean PC board can have 100 pA of leakage
currents between adjacent traces, so guard rings should be used
around the inputs. Guard traces are operated at a voltage close to
that on the inputs, as shown in Figure 7, so that leakage currents
become minimal. In noninverting applications, the guard ring
should be connected to the common-mode voltage at the inverting
input. In inverting applications, both inputs remain at ground,
so the guard trace should be grounded. Guard traces should be
on both sides of the circuit board.
PRECISION CURRENT PUMP
Maximum output current of the precision current pump shown
in Figure 10 is 10 mA. Voltage compliance is 10 V with 15 V
supplies. Output impedance of the current transmitter exceeds
3 MΩ with linearity better than 16 bits.
R3
10k⍀
R1
10k⍀
2
3
R6
10k⍀
1/2
OP297
1
I
OUT
10mA
R2
10k⍀
V
IN
+15V
8
5
R4
OPEN-LOOP GAIN LINEARITY
10k⍀
7
1/2
The OP297 has both an extremely high gain of 2000 V/mV
minimum and constant gain linearity. This enhances the precision
of the OP297 and provides for very high accuracy in high closed
loop gain applications. Figure 8 illustrates the typical open-loop
gain linearity of the OP297 over the military temperature range.
OP297
6
V
V
IN
IN
I
=
=
= 10mA/V
OUT
R5
100⍀
–15V
Figure 10. Precision Current Pump
R
= 10k⍀
= ؎15V
= 0V
L
V
V
S
CM
T
= +125؇C
A
T
= +25؇C
= –55؇C
A
0
T
A
–15
–10
–5
0
5
10
15
OUTPUT VOLTAGE (V)
Figure 8. Open-Loop Linearity of the OP297
REV. E
–7–
OP297
PRECISION POSITIVE PEAK DETECTOR
In Figure 11, the CH must be of polystyrene, Teflon®, or poly-
ethylene to minimize dielectric absorption and leakage. The
droop rate is determined by the size of CH and the bias current
of the OP297.
All the transistors of the MAT04 are precisely matched and at
the same temperature, so the IS and VT terms cancel, giving
2 ln IIN = ln IO + ln IREF = ln I × IREF
(
)
O
Exponentiating both sides of the equation leads to
2
1k⍀
I
(
=
)
IN
IO
+15V
IREF
1N4148
0.1F
Op amp A2 forms a current-to-voltage converter, which gives
VOUT = R2 × IO. Substituting (VIN/R1) for IIN and the above
equation for IO yields
2
3
8
1/2
6
5
1
OP297
1/2
OP297
7
1k⍀
V
V
IN
OUT
1k⍀
R2 VIN 2
0.1F
C
H
VOUT =
RESET
I
R1
REF
1k⍀
2N930
–15V
A similar analysis made for the square-root circuit of Figure 14
leads to its transfer function
Figure 11. Precision Positive Peak Detector
SIMPLE BRIDGE CONDITIONING AMPLIFIER
Figure 12 shows a simple bridge conditioning amplifier using the
OP297. The transfer function is
V
I
REF
(
IN )(
)
VOUT = R2
R1
C2
100pF
∆R RF
R2
33k⍀
VOUT =VREF
R + ∆R
R
6
The REF43 provides an accurate and stable reference voltage for
the bridge. To maintain the highest circuit accuracy, RF should
be 0.1% or better with a low temperature coefficient.
1/2
OP297
7
V
I
OUT
O
5
1
2
Q1
7
Q2
3
6
15V
5
MAT04E
R
14
F
V
REF
13
8
I
Q4
REF
9
C1
REF43
Q3
10
V+
100pF
12
2
R1
33k⍀
4
8
2
1/2
OP297
1
R3
V
IN
V
R + ⌬R
OUT
1/2
OP297
50k⍀
1
3
R4
50k⍀
3
4
–15V
8
V–
6
5
R
⌬R
R + ⌬R
F
1/2
OP297
7
V
= V
OUT
REF
R
Figure 13. Squaring Amplifier
4
R2
33k⍀
Figure 12. A Simple Bridge Conditioning Amplifier
Using the OP297
C2
100pF
6
NONLINEAR CIRCUITS
1/2
7
V
I
OUT
OP297
Due to its low input bias currents, the OP297 is an ideal log
amplifier in nonlinear circuits such as the square and square-
root circuits shown in Figures 13 and 14. Using the squaring
circuit of Figure 13 as an example, the analysis begins by writing a
voltage loop equation across transistors Q1, Q2, Q3, and Q4.
O
5
I
REF
MAT04E
1
3
Q1
6
14
Q4
12
13
C1
100pF
7
8
S1
IIN
I
IIN
IO
IREF
IS 4
9
Q2
Q3
10
V ln
+V ln
=VT3 ln
+VT 4 ln
V+
T1
T2
5
I
I
S2
S3
R1
33k⍀
8
2
R3
50k⍀
V
IN
1/2
1
OP297
R4
50k⍀
3
4
–15V
V–
Figure 14. Square-Root Amplifier
–8–
REV. E
OP297
In these circuits, IREF is a function of the negative power supply.
To maintain accuracy, the negative supply should be well regu-
lated. For applications where very high accuracy is required, a
voltage reference may be used to set IREF. An important consider-
ation for the squaring circuit is that a sufficiently large input voltage
can force the output beyond the operating range of the output
op amp. Resistor R4 can be changed to scale IREF, or R1, and R2
can be varied to keep the output voltage within the usable range.
OP297 SPICE MACRO MODEL
Figures 14 and 15 show the node end net list for a SPICE macro
model of the OP297. The model is a simplified version of the
actual device and simulates important dc parameters such as VOS
IOS, IB, AVO, CMR, VO, and ISY. AC parameters such as slew
rate, gain and phase response, and CMR change with frequency
are also simulated by the model.
,
The model uses typical parameters for the OP297. The poles
and zeros in the model were determined from the actual open-
and closed-loop gain and phase response of the OP297. In this
way, the model presents an accurate ac representation of the actual
device. The model assumes an ambient temperature of 25°C.
Unadjusted accuracy of the square-root circuit is better than 0.1%
over an input voltage range of 100 mV to 10 V. For a similar
input voltage range, the accuracy of the squaring circuit is better
than 0.5%.
99
V2
R3
R4
6
13
C4
C2
5
D3
12
R8
15
16
R
C
IN2
2
1
8
7
C3
G1
R7
R9
E1
Q1 Q2
10
–IN
+IN
R1
11
D1
D2
98
I
IN
3
R2
OS
R5 R6
4
E
D4
REF
14
V3
R
9
IN1
E
OS
I1
50
C6
C7
R11
R13
E2
E3
R10
R12
R14
R15
C5
C8
G1
G3
98
9
99
G6
D7
26
D8
R18
I
R16
23
SYS
V4
D5
22
25
L1
V5
D6
27
28 29
G4
R17
R19
G7
D9
D10
G5
50
Figure 15. Macro Model
REV. E
–9–
OP297
SPICE Net List
*OP297 SPICE MACRO-MODEL
*
*NODE ASSIGNMENTS
*POLE AT 1.8 MHz
*
R10
C5
G2
*
17
17
98
98
98
17
1E6
88 4E-15
16 23 1 E-6
NONINVERTING INPUT
INVERTING INPUT
OUTPUT
POSITIVE SUPPLY
NEGATIVE SUPPLY
*COMMON-MODE GAIN NETWORK WITH ZERO AT 50 HZ
*
R11
C6
R12
E2
*
18
18
19
18
19
19
98
98
1E6
3.183E-9
1
*SUBCKT OP297
*
*INPUT STAGE & POLE AT 6 MHz
*
1
2
30
99
50
3 23 100E-3
RIN1
RIN2
R1
1
2
8
7
8
3
3
99
99
8
6
50
8
7
8
9
4
4
9
8
2500
2500
5E11
5E11
612
612
3E-12
21.67E-12
0.1E-3
20E-12
POLY(1) 19 23 25E-6 1
10
11
96
96
DX
DX
*POLE AT 6 MHz
*
R15
C8
G3
*
22
22
98
98
98
22
1E6
26.53E-15
17 23 1 E-6
R2
7
R3
5
R4
6
CIN
C2
7
5
*OUTPUT STAGE
*
I1
4
R16
R17
ISY
R18
R19
L1
G4
G5
G6
G7
V4
23
23
99
25
25
25
28
29
25
50
26
25
22
27
99
99
50
50
99
50
50
99
50
30
50
50
99
25
25
27
26
22
28
29
28
29
160E3
160E3
331E-6
200
200
1E-7
22 25 5E-3
25 22 5E-3
99 22 5E-3
22 50 5E-3
1.8
1.3
DX
DX
DX
DX
DY
DY
IOS
EOS
Q1
7
9
5
QX
QX
Q2
6
R5
R6
D1
10
11
8
D2
9
*
EREF
*
98
0
23 0 1
V5
*GAIN STAGE & DOMINANT POLE AT 0.13 HZ
*
D5
D6
D7
D8
D9
D10
*
R7
C3
G1
V2
V3
D3
D4
*
12
12
98
99
14
12
14
98
98
12
13
50
13
12
2.45E9
500E-12
5 6
1.5
1.5
1.634E-3
DX
DX
*MODELS USED
*
.MODEL QX NPN BF=2.5E6)
.MODEL DX D IS = 1E-15)
.MODEL DY D IS = 1E-15 BV = 50)
.ENDS OP297
*NEGATIVE ZERO AT -1.8 MHz
*
R8
C4
R9
E1
*
15
15
16
15
16
16
98
98
1E6
–88.4E-15
1
12 23 1E6
–10–
REV. E
OP297
OUTLINE DIMENSIONS
8-Lead Plastic Dual In-Line Package [PDIP]
8-Lead Ceramic Dual In-Line Package [CERDIP]
P-Suffix
(N-8)
Z-Suffix
(Q-8)
Dimensions shown in inches and (millimeters)
Dimensions shown in inches and (millimeters)
0.005 (0.13) 0.055 (1.40)
0.375 (9.53)
0.365 (9.27)
0.355 (9.02)
MIN
MAX
8
5
8
1
5
0.310 (7.87)
0.220 (5.59)
0.295 (7.49)
0.285 (7.24)
0.275 (6.98)
PIN 1
1
4
4
0.325 (8.26)
0.310 (7.87)
0.300 (7.62)
0.100 (2.54) BSC
0.405 (10.29) MAX
0.100 (2.54)
BSC
0.320 (8.13)
0.290 (7.37)
0.150 (3.81)
0.135 (3.43)
0.120 (3.05)
0.060 (1.52)
0.015 (0.38)
0.015
(0.38)
MIN
0.180
(4.57)
MAX
0.200 (5.08)
MAX
0.150 (3.81)
0.015 (0.38)
0.010 (0.25)
0.008 (0.20)
0.200 (5.08)
0.125 (3.18)
MIN
0.150 (3.81)
0.130 (3.30)
0.110 (2.79)
0.022 (0.56)
0.018 (0.46)
0.014 (0.36)
SEATING
PLANE
0.015 (0.38)
0.008 (0.20)
0.023 (0.58)
0.014 (0.36)
SEATING
PLANE
15
0
0.070 (1.78)
0.030 (0.76)
0.060 (1.52)
0.050 (1.27)
0.045 (1.14)
CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETERS DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN
COMPLIANT TO JEDEC STANDARDS MO-095AA
CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETER DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN
8-Lead Standard Small Outline Package (SOIC)
Narrow Body
S-Suffix
(R-8)
Dimensions shown in millimeters and (inches)
5.00 (0.1968)
4.80 (0.1890)
8
1
5
4
6.20 (0.2440)
5.80 (0.2284)
4.00 (0.1574)
3.80 (0.1497)
0.50 (0.0196)
0.25 (0.0099)
1.27 (0.0500)
BSC
؋
45؇ 1.75 (0.0688)
1.35 (0.0532)
0.25 (0.0098)
0.10 (0.0040)
8؇
0.51 (0.0201)
0.31 (0.0122)
0؇ 1.27 (0.0500)
COPLANARITY
0.10
0.25 (0.0098)
0.17 (0.0067)
SEATING
PLANE
0.40 (0.0157)
COMPLIANT TO JEDEC STANDARDS MS-012AA
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN
REV. E
–11–
OP297
Revision History
Location
Page
7/03—Data Sheet changed from REV. D to REV. E.
Changes to TPCS 13 and 16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Edits to Figures 12 and 14 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Changes to NONLINEAR CIRCUITS Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
10/02—Data Sheet changed from REV. C to REV. D.
Edits to Figure 16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
10/02—Data Sheet changed from REV. B to REV. C.
Edits to SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Deleted WAFER TEST LIMITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Deleted DICE CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Deleted ABSOLUTE MAXIMUM RATINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Edits to ORDERING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Updated OUTLINE DIMENSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
–12–
REV. E
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