A wide swing 1.5 V fully differential op-amp using a rail-to-rail analog CMFB circuit

Abstract

Design and simulation results of a CMOS fully differential op amp using continuous time rail-to-rail CMFB are presented. In the conventional source follower CMFB circuits because of substantial level shift due to V/sub GS/ of source follower, outputs are restricted to have severed limited swing. In this paper two NMOS and PMOS CMFB are composed as complementary CMFBs to allow free output swing. The circuit is then simulated in 0.13 /spl mu/m CMOS technology and performance parameters, which have been obtained, are much better than conventional methods. 2.4 v Peak-to-Peak swing and a CMRR of 118 dB have been achieved.