I have a problem where I am passing pulses received from a photo-diode into a high pass RC filter. Circuit shown below.
The pulses are being received at 25Khz. Before the filter, the pulses are measured as expected. After the filter, the signal gets shifted as shown below and only seems to stabilize after around the 10th pulse. I assume that this is due to the RC time constant of the HPF.
This is a problem as I then amplify the signals after by an op-amp with a 0v cut off so I am then left with an inaccurate decaying signal.
The values of the capacitor and resistor in the HPF are selected to have a cut-off frequency of around 1500Hz.
Would anyone have a solution to this problem or some recommendations? It would be greatly appreciated. Can I change the filter in anyways to stop this signal shift? Thanks
The signal-not a great picture but the shift down can be seen. 
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