A 4^(th)-order low-pass filter(LPF) based on active-G_m-RC structure for multi-standard system application is presented in this paper.The performances of LPF are controlled by a 1-bit controlvoltage,and the cut-off frequency,channel selectivity,and linearity of the proposed filter can be reconfigured accordingly.In order to improve the accuracy of the cut-off frequency,a binary-weighted switched-capacitor array is employed as the auto-tuning circuits to calibrate the RC-time constant.Fabricated in TSMC 0.18μm RF CMOS process,the proposed LPF achieves a measured cutoff frequency of 1.95 and 12.3MHz for WCDMA and GPS/Galileo application with a bandwidth deviation less than 4%.The measured 1dB compression points are-3.0dBm and-5.1dBm respectively for different modes.The core circuit of LPF consumes 1mW and 1.6mW for WCDMA and GPS/Galileo respectively.And the proposed LPF occupies an area of 0.78mm^2.
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