Negative Feedback Programmable Charge Amplifier for Control Piezoelectric Sensors.

This paper describes the design and operation of a programmable charge amplifier for a piezoelectric sensor. An operational amplifier (op-amp) circuit operates the charge amplifier. The purpose of this paper was to design and explain a novel approach for programmable charge amplifiers. A programmable charge amplifier is created by a host digitally (Serial Peripheral Interface (SPI)) and a network of negative feedback, which is a network of resistors and capacitors (RC) connected between an output and inverter input node of an op-amp, where the feedback capacitor is 15 pF and resistors are 12.5, 25, 50, 100, and 200 k. The analog switch was used to connect serial to RC and subsequently to SPI. The suggested circuit was developed and evaluated using discrete components; also, the programmable circuit design and results were generated using Linear Technology's Integrated Circuit Emphasis (LTSPICE) simulation software. It is powered by a ±5V battery. The open loop (AOL), Noise Gain (NG), and phase margin have all been demonstrated in ac analysis. AOL and UGF are set for varied all switches (AOL 107.26 dB and UGF 8.6 MHz), however NG exhibits stability when the feedback capacitor is larger than 15 pF and the feedback resistance is fixed since the design has a Rate-Of-Closure (ROC) smaller than 20 dB. On the other side, the phase margin is also stable. When the switches (the 5-bits of SPI) are activated, the feedback capacitor is set to 15 pF, resulting in the optimum stability, output voltage, settling time, and slew rate. These have been completed in the time domain (transient analysis). [ABSTRACT FROM AUTHOR]