A Comparator-Based Switched-Capacitor Delta Sigma Modulator

Comparator-Based Switched-Capacitor (CBSC) is a relatively new topology that replaces opamps in sampled-data systems with a comparator and a set of current mirrors. CBSC is expected to lower power consumption, and to avoid several delicate tradeoffs of op-amp circuits. In this paper, the original single-ended CBSC block is extended to a fully differential version. The differential CBSC is then applied to an industrial standard second order delta-sigma modulator originally based on op-amps. Due to the differences between CBSC and op-amp, a few architectural changes are necessary for the original modulator. Finally, the performance of transistor level simulation of this CBSC based modulator is evaluated. Thesis Supervisor: Jeffrey Hinrichs Title: Staff Engineer, Qualcomm Thesis Supervisor: Joel L Dawson Title: Professor of Electrical Engineering, MIT