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AD8232 circuit (Figure. 66 - Circuit for ECG Waveform Monitoring) produces low 20dB gain on SPICE modeling. Why?

Question asked by nrbrtx@gmail.com on Nov 13, 2016
Latest reply on Feb 13, 2017 by Emman.A

Dear ADI!

 

I downloaded SPICE model of AD8232 and tested it with NI Multisim 14.

 

I got Gain vs. Frequency plots for Fig. 62 and Fig. 64. They are equal to your Fig. 63 and Fig. 65.
But when I try to model Fig. 66 I get gain <= 20 dB instead of 60 dB as on Fig. 67.

 

Here is my circuit:

Fig. 66 circuit in Multisim   

Here is frequency response:

Gain vs. Frequency in Multisim (AC Sweep)


I ran AC Sweep with RA as input, LA and RL are grounded (as while testing Fig. 62 and 64), frequencies as on your plots.
I compared my circuit with Fig. 66 many times, so I'm almost sure I do not have any error here.

 

Where am I wrong?

 

 

With best regards,
Norbert.

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