摘要：An analog baseband circuit of high linearity and high gain accuracy for a digital audio broadcasting receiver is implemented in a 0.18-μm RFCMOS *** circuit comprises a 3rd-order active-RC complex filter（CF） and a programmable gain amplifier（PGA）.An automatic tuning circuit is also designed to tune the CF＇s pass *** of the class-A fully differential operational amplifier（FDOPA） adopted in the conventional CF and PGA design,a class-AB FDOPA is specially employed in this circuit to achieve a higher linearity and gain accuracy for its large current swing capability with lower static current *** the PGA circuit,a novel DC offset cancellation technique based on the MOS resistor is introduced to reduce the settling time significantly.A reformative switching network is proposed,which can eliminate the switch resistor＇s influence on the gain accuracy of the *** measurement result shows the gain range of the circuit is 10-50 dB with a 1-dB step size,and the gain accuracy is less than ±0.3 *** OIP3 is 23.3 dBm at the gain of 10 *** results show that the settling time is reduced from 100 to 1 *** image band rejection is about 40 *** only draws 4.5 mA current from a 1.8 V supply voltage.