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Poor performance of active high pass filter at high gain using TLC2272A

Christopher Wiebe
Prodigy 70 points
Other Parts Discussed in Thread: TLC2272A

I am using the TLC2272A to design a Sallen-Key HPF. The target -3dB is 25 Hz. I have tried a few designs playing with the passband gain. The three gain values I have tried are x5, x25 and x50. I have noticed that at higher gain the HPF performance is poor, the -3dB point shifts to higher frequency and the low frequency roll-off is significantly less steep. Also at higher gain the passband does not reach the designed value. The following table summarizes what I found.

Config Max Gain f-3dB Roll-off
x5 5 27 Hz 33.82 dB/dec
x25 21.15 40 Hz 26.52 dB/dec
x50 34.85 110 Hz

18.17 dB/dec

Below is also a magnitude freq response plot. Blue = x5, Green = x25, Red = x50.

There is nothing obvious to me from the data sheet that would suggest this type of performance, also the simulations all check out using the TI provided SPICE file. Any ideas?