摘要：This paper presents the design and implementation of a fully integrated multi-band rf receiver frontend for GNSS applications on L-band.A single rf signal channel with a low-IF architecture is adopted for multi-band operation on the rf section,which mainly consists of a low noise amplifier（LNA）,a down-converter,polyphase filters and summing *** improved cascode source degenerated LNA with a multi-band shared off-chip matching network and band switches is implemented in the first amplifying ***,a re-designed wideband double balance mixer is implemented in the down conversion stage,which provides better gain,noise figure and linearity *** a TSMC 0.18μm 1P4M rf CMOS process,a compact 1.27 GHz/1.575 GHz dualband GNSS frontend is realized in the proposed low-IF *** measurements exhibit the gains of 45 dB and 43 dB,and noise figures are controlled at 3.35 dB and 3.9 dB of the two frequency bands,*** frontend model consumes about 11.8-13.5 mA current on a 1.8 V power *** core occupies 1.91×0.53 mm2 while the total die area with ESD is 2.45×2.36 mm^2.