Feedback control for a MEMS-based high-performance operational amplifier

A novel MEMS-based operational amplifier that uses extensive feedback control techniques to achieve robust performance is described. The input stage of the amplifier is a MEMS structure that provides a variable capacitance to transduce a low-frequency input voltage into a high-frequency AC current. This up-modulation of the input signal is exploited to reduce offsets and low-frequency noise, and the dielectric isolation of the MEMS structure provides high input impedance and low leakage currents. This paper details the closed-loop designs used to implement the signal up-modulation and to provide accurate gain to the input.