I am trying to design an Active Band Pass filter, to pass frequencies 60Hz (220 v electricity noise) to 20K, part of ADC system. My source signal is coming from Piezoelectric sensor, which means more than 100K ohm impedance, whith volatage levels between 100/200 mv p-p. i'd like to get output voltage of 1V p-p I would like to build the buffer to 'translate' the impedance into a very low impedance.
limitation : 1 single 5v power supply.
I am using MCP6021/6022/6024 opamp , for the unity gain active filtering, and TI PGA2311 to apply the configurable gain.
and I tried to integrate this circuit with the PGA, So my current design absence that my negative voltage is getting cut (the source signal has no offset...) So I need your help in the following problems : 1. how to create a DC bias? 2. how to improve the LPF ? i tried to simulate with CircuitLab and i get not the best graph... 2. how to add HPF to filter bellow 60hz?
Thanks a lot.