Highly linear CMOS triode transconductor for VHF applications

A high-speed, fully balanced complementary-symmetry metal-oxide-semiconductor (CMOS) triode transconductor is presented. The proposed approach exploits a pseudo-differential-pair triode configuration with a simple adaptive circuit stabilising the drain-to-source voltages of metal-oxide-semiconductor (MOS) transistors. Since no additional active circuits (apart from the resistors made of the cut-off MOS devices) and no feedback loop are used, linearisation improvement is obtained without compromising bandwidth and power consumption. The non-linearity because of the mobility degradation is also compensated. The transconductance of the proposed transconductor can be up to several times higher than for the classical topologies with no extra power consumption. As an example, the transconductor is used to design sixth-order elliptic band-pass filter in the very-high-frequency (VHF) range, simulated in a 0.35 mu m CMOS process (AMS).