A Realization of Low Noise Silicon Acoustic Transducer Interface Circuit

An interface circuit dedicated for silicon acoustic transducer is presented. The circuit includes a transimpedance amplifier for the impedance matching between the acoustic sensor and the negative feedback amplifier along with a negative feedback amplifier with a fixed gain for pre-amplifying the acoustic signal. The input stage of the negative feedback amplifier is specially designed to satisfy sensor's specifications and avoid low frequency noise. The circuit is implemented in a standard CMOS process, and measurements with a conventional silicon microphone are taken. The interface circuit achieves 20dB gain, and a SNR of 51dB with an A-weighted output noise of-119dBV. Results shown in this article validates the circuit designed.