Jun 29, 2011 #21 F ffsher100 Junior Member level 3 Joined Jun 16, 2011 Messages 27 Helped 1 Reputation 2 Reaction score 1 Trophy points 1,283 Activity points 1,486 Hi Lvw, the large resistor & cap. DC feedback is good idea.
Jun 30, 2011 #22 F ffsher100 Junior Member level 3 Joined Jun 16, 2011 Messages 27 Helped 1 Reputation 2 Reaction score 1 Trophy points 1,283 Activity points 1,486 Hi Lvw, LvW said: Example: Rf=100 kohms, C=100 Farad result in a lower cut-off frequency of app. 16 mHz. Click to expand... the cut-off frequency in example should: 1/(10^5 * 10^2 * 2*pi)= 10^(-7) * 0.16= 16nHz, not 16mHz
Hi Lvw, LvW said: Example: Rf=100 kohms, C=100 Farad result in a lower cut-off frequency of app. 16 mHz. Click to expand... the cut-off frequency in example should: 1/(10^5 * 10^2 * 2*pi)= 10^(-7) * 0.16= 16nHz, not 16mHz
Jun 30, 2011 #23 LvW Advanced Member level 6 Joined May 7, 2008 Messages 5,912 Helped 1,753 Reputation 3,512 Reaction score 1,364 Trophy points 1,393 Location Germany Activity points 40,432 ffsher100 said: Hi Lvw, the cut-off frequency in example should: 1/(10^5 * 10^2 * 2*pi)= 10^(-7) * 0.16= 16nHz, not 16mHz Click to expand... Hi ffsher100, the R-C feedback creates an active highpass - H(s)=Amax/(1+s/RC) - with a maximum gain Amax that depends on the opamp type. Thus, you have to multiply with 1E5...1E6.
ffsher100 said: Hi Lvw, the cut-off frequency in example should: 1/(10^5 * 10^2 * 2*pi)= 10^(-7) * 0.16= 16nHz, not 16mHz Click to expand... Hi ffsher100, the R-C feedback creates an active highpass - H(s)=Amax/(1+s/RC) - with a maximum gain Amax that depends on the opamp type. Thus, you have to multiply with 1E5...1E6.