I need ideas for buffering a low capacitance sensor (
Buffering low capacitance sensors (<50 pF)
Mar 30, 2006
10 Replies
The non-inverting input resistance does not necessarily have to match the inverting input resistance. It depends on how much error that you can tolerate due to input bias current. The equation for output error due to input bias current is: . Vob = IbRf(1-Rni/Rinv) Where . Vob is the output error due to bias current . Ib = input bias current . Rf = Equivalent feedback resistance . Rni = Equivalent resistance "seen" by non-inv input . Rinv = Equivalent resistance "seen" by inv input
Thanks, good idea, did some simulations. Have to be carefull otherwise the circuitry turns into a oscillator.
I do not have stringent DC offset requirements. The sensor used is small area PVDF pressure sensor (capacitance usually less then
I meant CLC425. I think the OPA656 has not so good noise figures
This is what I do know, I tolerate a certain output error but due to this there is a limitation in this Rf
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