A zero-crossing switched-capacitor filter design

Abstract

Design of switched capacitor circuits in scaled CMOS technologies is becoming difficult because of low device intrinsic gain and reduced power supply voltage. To solve these problems, comparator-based switched-capacitor (CBSC) circuits and zero-crossing based circuits (ZCBC) were suggested as a possible solution to the op-amp based circuits. In this thesis, we explore zero-crossing based circuits (ZCBC) in high-order differential switched-capacitor filters to replace area inefficient op-amps-based continuous-time baseband filters. For the prototype for the zero-crossing based high-order switched capacitor filter, a low-pass ladder filter network will be used which is less sensitive to component variations. Several transformation steps from this low-pass passive ladder filter network to a differential high-order switched capacitor filter will be explored. To verify this architecture, SWITCAP will be used. And then ZCBC circuit implementation in Cadence will be explored.