A Nonlinear OTA Simulation Model for the Design of a Switched-Capacitor DSM

C.-Y. Yao, J.-Y. Wu (National Taiwan Univ. of Science and Techn., Taiwan)

This paper proposes a nonlinear simulation model of an operational transconductance amplifier (OTA) for switched-capacitor (SC) delta-sigma modulators (DSMs). A worst-case condition is assumed to characterize the nonlinear behavior of the OTA gain. Under this assumption, the OTA input-output relationship is analytically derived and incorporated into a Simulink-based SC DSM model. The resulting simulation outcomes are then compared with experimental measurements obtained from a fabricated SC DSM chip, thereby validating the effectiveness of the proposed modeling approach and methodology.