Bipolar/CMOS (weak inversion) rail-to-rail constant-gm input stage
A rail-to-rail constant-gm input stage suitable for bipolar or weak inversion CMOS implementation is presented. To achieve rail-to-rail operation, two complementary differential pairs driven in parallel are used. To guarantee constant net transconductance each differential pair is augmented with a suitable biasing circuit. The biasing circuits are implemented without current mirrors, which results in low sensitivity to process variations and potentially higher bandwidth.
