A low power baseband chain for CMMB application

This paper presents experimental results of an analog baseband circuit for China multimedia mobile broadcasting (CMMB) direct conversion receiver in 0.35 um SiGe BiCMOS process. It is the first baseband of CMMB RFIC reported so far. A 8^th-order chebyshev low pass filter (LPF) with calibration system is used in the analog baseband circuit, the filter provides 0.5 dB passband ripple and -35 dB attenuation at 6 MHz with the cutoff frequency at 4 MHz, the calibration of filter is reported to achieve the bandwidth accuracy of 3%. The baseband variable gain amplifier (VGA) achieves more than 40 dB gain tuning with temperature compensation. In addition, A DC offset cancellation circuit is also introduced to remove the offset from layout and self-mixing, and the remaining offset voltage and current consumption are only 6 mV and 412 uA respectively. Implemented in a 0.35 um SiGe technology with 1.1 mm² die size, this tuner baseband achieves OIP3 of 25.5 dBm and dissipate 16.4 mA under 2.8-V supply.