A 50- to 300-MHz CMOS <inline-formula> <tex-math notation="LaTeX">$Gm\mbox{-}C$</tex-math></inline-formula> Tracking Filter Based on Parallel Operation of Saturation and Triode Transconductors for Digital TV Tuner ICs

Abstract

In this brief, a 50- to 300-MHz CMOS Gm-C tracking low-pass filter has been presented to resolve a LO harmonic-mixing problem for Advanced Television Systems Committee terrestrial and cable digital TV tuner integrated circuits. A Gm-C filter based on parallel operation of a transconductor biased in the saturation region with source degeneration and a transconductor biased in the triode region is chosen to achieve high linearity performance at the very high frequency/ultrahigh frequency bands. The cutoff frequency of the proposed filter is tunable from 50 to 300 MHz. The filter is implemented in a 0.18-μm CMOS technology and achieves a minimum input-referred noise density of 3 nV/√Hz and maximum in-band output-referred third-order intercept point of 20.7 dBm. It operates at a nominal supply voltage of 1.8 V with bias currents of 114 mA. The active die area is 1.1 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .