A 50-300-MHz low power and high linear active RF tracking filter for digital TV tuner ICs

A low power and highly linear CMOS active tracking bandpass filter is presented to overcome a local oscillator harmonic mixing problem for Digital TV tuner ICs. A transconductor linearization technique based on a method of dynamic source degenerated differential pair is adopted to improve the linearity performance. The newly proposed low power high quality factor (Q) biquad and the linearized transconductor with negative resistance load (NRL) enables a low power and high Q RF tracking filter design. The total chip area is 0.25 mm X 0.9 mm. The fabricated tracking filter based on the 0.13 um CMOS process shows 48~300 MHz tracking range with 10~50 MHz bandwidth, more than 38 dB 3rd order harmonic rejection, 6 dB unwanted signal rejection@N+6 channel offset, and a maximum IIP3 of 6 dBm at 5 dB gain while drawing 6.4 mA from a 1.2 V supply.