Integrated low voltage and low power CMOS circuits for optical sensing of diffraction based micromachined microphone

We present CMOS electronics for optical sensing of diffraction based micromachined microphone. Peak detector and track and hold circuits are used for continuous time approach with only 58 μA of current for 65dB peak SNR (lPa at 1kHz). We also present a 1-bit sigma delta interface ADC for directly digitizing the signal for digital processing with 63 μA of current for 62dB peak SNR (lPa @ 1kHz). The electronics are designed in 0.35um standard digital CMOS process with reduced supply of 1.5Volts. All the analog front end circuits operate in weak inversion with rail-to-rail wide input linear range.