VHF fully-differential linearized CMOS transconductance element and its applications

The design of a fully-differential highly linear, voltage-tunable CMOS transconductance element with improved gain performance and wide bandwidth is described. A negative resistance load (NRL) technique for compensation of the parasitic output resistance of the transconductor circuit is employed without requiring extra internal nodes. Owing to this, the DC-gain enhancement is obtained without any penalty in the bandwidth. An improved transconductance circuit is presented with its application to third-order transconductance-capacitor (C) filter in the very high frequency (VHF) range assuming implementation in a standard 3 /spl mu/m CMOS process. The cutoff frequency of the filter is tunable in the range of 9.7-48.4 MHz. The filter total harmonic distortion (THD) is lower than -50 dB for an output signal up to 1V/sub p-p/ at 5 MHz frequency has been predicted via SPICE simulation.