OP177_06 Datasheet, PDF (12/16 Pages) Analog Devices – Ultraprecision Operational Amplifier

OP177
PRECISION POSITIVE PEAK DETECTOR
In Figure 31, CH must be polystyrene, Teflon®, or polyethylene
to minimize dielectric absorption and leakage. The droop rate is
determined by the size of CH and the bias current of the AD820.
PRECISION THRESHOLD DETECTOR/AMPLIFIER
In Figure 32, when VIN < VTH, amplifier output swings negative,
reverse biasing diode D1. VOUT = VTH if RL = ∞. When VIN ≥
VTH, the loop closes.
V_OUT
= V_TH
+ (V_IN
− V_TH )_{⎜⎜⎝⎛}1 +
R_F
R_S
⎟⎟⎠⎞
CC is selected to smooth the response of the loop.
R_S
1kΩ
V_TH
R₁
2kΩ
V_IN
C_C
R_F
100kΩ
+15V
0.1µF
2_– 7
OP177 ⁶
3₊
4 _0.1µF
D₁
1N4148
V_OUT
–15V
Figure 32. Precision Threshold Detector/Amplifier
Rev. E | Page 12 of 16