OP77_02 Datasheet, PDF (11/16 Pages) Analog Devices – Next Generation OP07 Ultralow Offset Voltage Operational Amplifier

APPLICATIONS INFORMATION
+15V
R2
1M⍀
0.1␮F
R1
2
7
1k⍀
OP77E ⁶
R3
3
1k⍀
4
0.1␮F
R4
1M⍀
–15V
Figure 7. Precision High-Gain Differential Amplifier
The high gain, gain linearity, CMRR, and low TCVos of the
OP77 make it possible to obtain performance not previously
available in single-stage very high-gain amplifier applications.
For best CMR,
R1
R2
must equal
R3
R4
.
In
this
example,
with a 10 mV differential signal, the maximum errors are as listed
in Table I.
Table I. Maximum Errors
TYPE
COMMON-MODE VOLTAGE
GAIN LINEARITY, WORST CASE
TCVOS
TCI OS
AMOUNT
0.01%/V
0.02%
0.003%/∞C
0.008%/∞C
Bilateral Current Source
R3
1k⍀
OP77
R1
V_IN
100k⍀
R2
100k⍀
2
OP77 ⁶
3
R4
990⍀
I_OUT < 15mA
R5
10⍀
Figure 9. Basic Current Source
R3
+15V
R1
V_IN
R2
2
OP77 ⁶
3
2N2222
2N2907
R5
R4
–15V
I_OUT < 100mA
( ) ^R3
I_OUT = V_{IN R1 – R5}
GIVEN R3 = R4 ؉ R5, R1 = R2
Figure 10. 100 mA Current Source
These current sources will supply both positive and negative
current into a grounded load.
Note that
Z_O
=
R5
ÊËÁ
R4
R2
+
1^ˆ¯˜
R5 + R4 R3
R2 R1
and that for Z_O to be infinite,
R_S
INPUT
R_F
10pF
+15V
0.1␮F
2
7
OP77 ⁶
3
4
0.1␮F
100⍀
OUTPUT
C_LOAD
–15V
Figure 8. Isolating Large Capacitive Loads
This circuit reduces maximum slew-rate but allows driving
capacitive loads of any size without instability. Because the boon
resistor is inside the feedback loop, its effect on output imped-
ance is reduced to insignificance by the high open-loop gain
of the OP77.
REV. C
–11–