Authors : Asha K. A. , Veda Sandeep Nagaraja and S. L. Pinjare
ACMOS preamplifier for MEMS directional microphone is presented in this paper. The preamplifier is realized in 180um technology with impedance matching between the microphone and preamplifier. A PMOS input two-stage opamp with miller compensation is designed as the gain stage with an open loop gain of 60dB. Two-stage opamp is configured as a differential input/output amplifier to amplify the weak differential signals from the directional microphone. A PMOS source-follower buffer is designed as the impedance matching network between the microphone and preamplifier. Preamplifier operates at a supply voltage of 1.8V.
Keywords : Differential input/output amplifier, Impedance matching, MEMS microphone, Preamplifier