A baseband LPF for GSM,TD-SCDMA and WCDMA multi-mode transmitters  

作　　者：余永长 韩科锋 王丽芳 谈熙 闵昊 

机构地区：[1]State Key Laboratory of ASIC & System,Fudan University

出　　处：《Journal of Semiconductors》2011年第2期85-90,共6页半导体学报（英文版）

基　　金：Project supported by the Important National Science & Technology Specific Projects(No.2009ZX01031-003-002);the National High Technology Research and Development Program of China(No.2009AA011605)

摘　　要：This paper describes a low-pass reconfigurable baseband filter for GSM, TD-SCDMA and WCDMA multi-mode transmitters. To comply with 3GPP emission mask and limit TX leakage at the RX band, the out- of-band noise performance is optimized. Due to the distortion caused by the subthreshold leakage current of the switches used in capacitor array, a capacitor bypass technique is proposed to improve the filter＇s linearity. An automatic frequency tuning circuit is adopted to compensate the cut-off frequency variation. Simulation results show that the filter achieves an in-band input-referred third-order intercept point （IIP3） of 47 dBm at 1.2-V power supply and the out-of-band noise can meet TX SAW-less requirement for WCDMA ＆ TD-SCDMA. The baseband filter incorporates -40 to 0 dB programmable gain control that is accurately variable in 0.5 dB steps. The filter＇s cut-off frequency can be reconfigured for GSM/TD-SCDMA/WCDMA multi-mode transmitter. The implemented baseband filter draws 3.6 mA from a 1.2-V supply in a 0.13 μm CMOS process.This paper describes a low-pass reconfigurable baseband filter for GSM, TD-SCDMA and WCDMA multi-mode transmitters. To comply with 3GPP emission mask and limit TX leakage at the RX band, the out- of-band noise performance is optimized. Due to the distortion caused by the subthreshold leakage current of the switches used in capacitor array, a capacitor bypass technique is proposed to improve the filter＇s linearity. An automatic frequency tuning circuit is adopted to compensate the cut-off frequency variation. Simulation results show that the filter achieves an in-band input-referred third-order intercept point （IIP3） of 47 dBm at 1.2-V power supply and the out-of-band noise can meet TX SAW-less requirement for WCDMA ＆ TD-SCDMA. The baseband filter incorporates -40 to 0 dB programmable gain control that is accurately variable in 0.5 dB steps. The filter＇s cut-off frequency can be reconfigured for GSM/TD-SCDMA/WCDMA multi-mode transmitter. The implemented baseband filter draws 3.6 mA from a 1.2-V supply in a 0.13 μm CMOS process.

关 键 词：active-RC filter multi-mode transmitter analog baseband tuning circuit 

分 类 号：TN929.53[电子电信—通信与信息系统]