A Current-Feedback Amplifier with Programmable Gain for MEMS Microphone Read-Out Circuits

This work presents a read-out amplifier for capacitive sensors, in particular for MEMS microphones, based on a current-feedback topology. This architecture allows for an extensive gain range while keeping the input impedance as well as the amplifier bandwidth independent of the selected gain. Noise performance is maximized and signal attenuation due to parasitic effects is minimized and stays constant at all gain settings. This architecture has been used for the design of an interface circuit for a MEMS microphone in a standard 0.13µm CMOS process.