Non-constant active filter gain with LTC 2065

Question

I designed an amplifier using an instrumentation amplifier and an operational amplifier. Here, I used a 2 Hz multifeedback high pass and 100 Hz multifeedback low pass filter, but I could not get the efficiency I expected from my filters. What I need is for the pass band between 2 Hz and 100 Hz to have a constant gain, unfortunately, I can only have the constant gain I want between 15 Hz and 30 Hz. I tried to visually express the problem I was experiencing in the third image. 
 I would like your solutions and suggestions on where I should focus to improve the response of the filters.

maaarmas · Accepted Answer

Hi, 
 Based on the previous question, someone from our team suggested to replace the R5 in your circuit to adjust the gain. This would shift the frequency response to a higher gain value and would amplify the output. For further details, you can check attached link. 
 Link: LTC 2065 is not working between 2 V - 4 V power supply - Q&A - Operational Amplifiers - EngineerZone (analog.com) 
 Then can you share your findings after adjusting the value of R5? 
 Thank you! 
 Regards, 
 Mae)

Partner Forums

Partner Libraries

Products Mentioned

Non-constant active filter gain with LTC 2065