Signal Conditioning Amplifier for Piezofilm Sensor
The signal can be converted by piezoelectric films in many ways such as thermal to electrical (temperature sensor), mechanical to electrical (microphone), and electrical to mechanical ( a loudspeaker). The circuit is signal conditioning amplifier for piezofilm sensor which use three op amps and has a high-input-impedance differential charge. Here is the circuit :
This circuit use a voltage source with a capacitor in series as the electrical analog of a piezofilm sensor. The differential charge amplifier is endowed by a dual op amp (IC1) with low supply current and single-supply operation . The input common-mode voltage is set by a small bypass capacitor (C3), R2, R1 at the mid-supply level. The C1 and C2 are used to set AC gain for the differential stage. A gain of C1/CEQ is 96.
The differential amplifier also is used to act as a first-order high-pass filter. The resistors R9, R8, R6, and R5 with IC2 perform differential-to-single-ended conversion. Using the values shown, the different gain is 20. [Source: maxim-ic.com]