Nested-Oversampling Successive Approximation (OSA) Technique for Readout Circuit of MEMS Capacitive Accelerometer

Abstract

Nested oversampling successive approximation (Nested-OSA) technique is proposed in this paper. This technique provides enhancement in the effective accuracy of the readout circuit for microelectromechanical systems (MEMS) capacitive accelerometer. The readout circuit with Nested-OSA technique contains a main switchedcapacitor amplifier which achieves capacitance-to-voltage conversion and an auxiliary switched-capacitor amplifier which suppresses the “holding error” appears in OSA process. The approach reduces the DC gain error and DC offset of amplifier to 4-order infinitesimal and 2-order infinitesimal. The charge injection and dynamic settling process of the Nested-OSA readout circuit are explained in detail. Theoretical analysis and simulations show that the suppression of gain error and offset of readout circuit using the Nested-OSA technique can be achieved while consume relatively low power.