ROIC for MEMS microhpone sensor

Abstract

A read-out integrated circuit (ROIC) for a microelectromechanical systems (MEMS) microphone sensor was designed in a 0.6 um CMOS process, fabricated and tested. The ROIC consists of a charge pump, a relaxation oscillator, a low-drop-out (LDO) regulator, a source follower and a variable gain amplifier; the charge pump generates a high DC voltage ranging from 7.8 V to 13 V in 32 linear steps from a 4.7 V DC output of the LDO regulator, the variable gain amplifier gives a voltage gain ranging from -3 dB to 6 dB in 16 linear steps, and the relaxation oscillator supplies a 1.2 MHz clock signal to the charge pump. The measurements of the ROIC show the A-weighted SNR of 64.7 dB, the total harmonic distortion (THD) of 0.006 %, and the power consumption of 1.9 mW at 5 V supply, with a 1 kHz 18.9 mV-amplitude sinusoidal input voltage. The active chip area is 4.6 mm^2.