AD544 AD [Analog Devices], AD544 Datasheet - Page 10

• Manufacturer Part Number: AD544
• Description: High Performance, BiFET Operational Amplifiers
• Manufacturer: AD [Analog Devices]

AD542/AD544/AD547
This particular log ratio circuit is free from the dynamic prob-
lems that plague many other log circuits. The –3 dB bandwidth
is 50 kHz over the top 3 decades, 100 nA to 100 A, and de-
creases smoothly at lower input levels. This circuit needs no ad-
ditional frequency compensation for stable operation from
input current sources, such as photodiodes, that may have 100
pF of shunt capacitance. For larger input capacitances a 20 pF
integration capacitor around each amplifier will provide a
smoother frequency response.
Figure 34. Differentiator
Figure 37. Capacitance
Multiplier
Figure 38. Long Interval
Timer–1,000 Seconds
Figure 35. Low Drift Integrator and
Low Leakage Guarded Reset
–10–
This log ratio amplifier can be readily adjusted for optimum
accuracy by following this simple procedure. First, apply V1 =
V2 = –10.00 V and adjust “Balance” for V
apply V1 = –10.00 V, V2 = –1.00 V and adjust gain for V
+1.00 V. Repeat this procedure until gain and balance readings
are within 2 mV of ideal values.
Figure 39. Positive Peak Detector
Figure 36. Wien-Bridge
Oscillator–f
O
OUT
= 10 kHz
= 0.00 V. Next
REV. B
OUT
=