ADA4620-1ARZ-R7 datasheet(37/49 Pages) AD

Part #	ADA4620-1ARZ-R7

Description	36 V, Precision, Low Noise, 16.5 MHz JFET Op Amp with Rail-to-Rail Output

PDF	49 Pages

Scroll/Zoom	100%

Manufacturer	AD [Analog Devices]

Direct Link	http://www.analog.com

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37 / 49 page

Data Sheet

ADA4620-1, ADA4620-2

analog.com

Rev. 0

37 of 49

Figure 117. Ideal Gain and Phase Plot of the Transimpedance Amplifier Design with Compensation

The gray trace in Figure 117 shows the ideal noise gain over frequencies for the photodiode preamp. Calculate the

noise bandwidth at the fN frequency by:

��

�� =

��

(�� + ��)/��

(7)

In reality, noise gain is limited by the gain bandwidth of the op amp, and rolls off with open-loop gain. The gray

trace in Figure 118 shows a more realistic noise gain plot, compared to Figure 117.

Figure 118. Attenuated Noise Gain, with Attenuation Following Open-Loop Gain

OPEN-LOOP GAIN

I-TO-V GAIN

NG = 1

G = 1 + CS/CF

fGBP

0°

45°

–45°

90°

–90°

–135°

NG = RFCFs

OPEN-LOOP GAIN

NG = 1 + CS/CF

NG = RFCFs

NG = 1

log f

ADA4620-1ARZ-R7 Datasheet(PDF) 37 Page - Analog Devices