Design of a high linearity and high gain accuracy analog baseband circuit for DAB receiver  

作　　者：马力 王志功 徐建 吴毅强 王俊椋 田密 陈建平 

机构地区：[1]Institute of RF-and OE-ICs, Southeast University

出　　处：《Journal of Semiconductors》2015年第2期124-129,共6页半导体学报（英文版）

基　　金：Project supported by the National Natural Science Foundation of China(Nos.61106024,61201176);the Specialized Research Fund for the Doctoral Program of Higher Education,China(No.20090092120012);the Special Fund of Jiangsu Province for the Transformation of Scientific and Technological Achievements(No.BA2011009)

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 process.The 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 band.Instead 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 consumption.In 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 PGA.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 dB.The OIP3 is 23.3 dBm at the gain of 10 dB.Simulation results show that the settling time is reduced from 100 to 1 ms.The image band rejection is about 40 dB.It only draws 4.5 mA current from a 1.8 V supply voltage.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 process.The 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 band.Instead 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 consumption.In 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 PGA.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 dB.The OIP3 is 23.3 dBm at the gain of 10 dB.Simulation results show that the settling time is reduced from 100 to 1 ms.The image band rejection is about 40 dB.It only draws 4.5 mA current from a 1.8 V supply voltage.

关 键 词：complex filter automatic tuning PGA RECEIVER DAB DCOC 

分 类 号：TN851[电子电信—信息与通信工程]