Abstract: 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 circuits. An improved cascode source degenerated LNA with a multi-band shared off-chip matching network and band switches is implemented in the first amplifying stage. Also, a re-designed wideband double balance mixer is implemented in the down conversion stage, which provides better gain, noise figure and linearity performances. Using a TSMC 0.18μm 1P4M RF CMOS process, a compact 1.27 GHz/1.575 GHz dual-band GNSS frontend is realized in the proposed low-IF topology. The 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, respectively. The frontend model consumes about 11.8–13.5 mA current on a 1.8 V power supply. The core occupies 1.91 × 0.53 mm² while the total die area with ESD is 2.45 × 2.36 mm².

Key words: low power, low IF, multi-band, noise figure, RF frontend, mixer, 低噪声放大器, CMOS, 卫星导航, GPS, 格洛纳斯系统, 北斗