Hello I´m trying to acondicionate small signal to mi ADC with a simple stage of two op amp TLV2264 with hight pass filter this is mi schematic:
As I think I make the calculation of the condenser to have an hight pass filter with cut frecuenci on 159 Hz with 6dB/oct not 12. But the gain until 400 or 500 hz are smaller than the teorical gain.
I was testing op amps TLV2264 on a single supply (see schematics)
With the right imput and no saturating, The circuit give me an output with gain of 10 each stage, a total of 100= 40dB. That is right but is only in frecuencies biger than 400hz (and lower than 300KHz it is enaff ), when you start to go down with the frecuency generator under 400 Hz the gain start to go down. Acording to mi calculations the gain must be linear on 10x by stage until 159Hz (when the hight pass filter starts to work).
Y had changed the condenser C1 of a midle value (50nf is 75hz teorical hight cut frecuency) but the unilineality of the gain are exactly the same. Under 400 Hz the gain starts to go down, it must start to ocurre under 159 not 400 Hz.
Could somebody tell me the reason of this unilineality??
Many thanks Aren
