CMOS continuous-time CMFB circuit with improved linearity

A continuous-time common-mode feedback (CMFB) network consisting of two unity-gain buffers and two passive resistors is introduced in this paper. According to the comparison with a previous implementation, the common-mode control structure presented shows an improved linearity performance as well as a higher immunity to device mismatches. The CMFB circuit has been included in the design of a fully differential voltage buffer, based on a fully differential difference amplifier. Simulated results, obtained in a 0.35-μm standard CMOS technology, are provided in order to show the performance of the proposed approach.