A 3-band CMOS DTV Tuner IC for DVB-C Receiver

A 3-band DTV tuner IC for DVB-C is designed in 0.25-mum CMOS process in this paper. The IC integrates not only mixer, PLL, but also an IF variable-gain amplifier. The mixer is based on Gilbert cell, and a transconductance linearization scheme is adopted to realize the highly linear, wide-range CMOS IF variable-gain amplifier with exponential gain control. A novel analog automatic amplitude controller based on charge-pump is proposed to stabilize performance across the 900-MHz tuning range without degrading the phase noise of VCO. An improved dual-module prescaler has wideband high input sensitivity. With 3.3 V supply voltage, the measurements show that the mixer has voltage gain of 35 dB, the variable-gain amplifier provides continuous gain control range of 40dB, a C/IM3 of 61.2 dBc at 1-Vpeak-to-peak output, and the phase noise is below -82dBc/Hz at the 10 kHz offset frequency within the whole tuning range. The STB based on the designed IC has received cable DTV clearly.