A high-linear wide-tunable CMOS transconductor for video frequency applications

摘要

In this paper a new CMOS transconductor structure based on a g_m-boosted degenerated differential pair is presented for applications in the video frequency range. The proposed circuit combines two techniques, a switchable array of source degenerating MOS resistors and a programmable output current mirror, in order to widen the G_m tuning range while maintaining linearity. Degeneration MOS resistors are made common-mode voltage independent thanks to a simple control circuit. Post-layout simulation results from a 0.35 μm design supplied at 3.3 V show a wide tuning range (10-100 MHz), good linearity (-58.4 dB for an output signal voltage of 1.1 V_(p-p)) and low excess phase (<0.5° over the whole tuning range).