Low-voltage rail-to-rail bulk-driven CMFB network with improved gain and bandwidth

A rail-to-rail CMOS continuous-time common-mode feedback (CMFB) network is introduced in this paper. The proposed scheme is based on the joint use of bulk-driven MOS transistors, which lead to high signal swing, and a partial positive feedback, which allows achieving enhanced DC gain and gain-bandwidth product. The proposed CMFB circuit is used to control the output voltage of a fully differential operational transconductance amplifier. Simulated results in standard 0.35-µm CMOS technology demonstrate the suitability of the approach.