A Low Power and Low Noise On-Chip Active RF Tracking Filter for Digital TV Tuner ICs

In this paper, a highly linear and low noise CMOS active RF tracking filter for a digital TV tuner is presented. The Gm cell of the Gm − C filter is based on a dynamic source degenerated differential pair with an optimized transistor size ratio, thereby providing good linearity and high-frequency operation. The proposed RF tracking filter architecture includes two complementary parallel paths, which provide harmonic rejection in the low band and unwanted signal rejection in the high band. The fabricated tracking filter based on a 0.13 μm CMOS process shows a 48∼860 MHz tracking range with 30–32 dB 3rd order harmonic rejection, a minimum input referred noise density of 2.4 nV/ √ Hz, and a maximum IIP3 of 0 dBm at 3 dB gain while drawing 39 mA from a 1.2-V supply. The total chip area is 1 mm × 0.9 mm. key words: CMOS, on-chip, DTV tuner, active RF tracking filter, transconductance-c filter (Gm-C filter), low-pass filter (LPF)