RF front-end architecture for a triple-band CMOS GPS receiver

This paper describes a triple-band global positioning system (GPS) receiver that simultaneously covers the L1, L2, and L5 frequency bands. The proposed receiver uses an image-rejection technique that can separate signals from the three frequency bands to three corresponding ports. It uses a single RF path containing a low-noise amplifier (LNA), and active and passive mixers with a pair of local oscillator signals. A triple-band GPS RF front-end chip was fabricated using 130 nm CMOS technology. The noise figure of this chip is less than 7 dB and its S11 coefficient is less than −10 dB in the 1.15-1.6 GHz frequency range. The power consumption of the LNA and mixers is 7.2 mW when using a 1.2 V supply voltage. The image-rejection ratio (IMRR) between L1 and the other (L2 and L5) band signals is 40 dB, while that between the L2 and L5 signals is 37-38 dB. To improve the IMRR between the L2 and L5 signals, we investigated the utilization of a digital compensation technique. This technique was confirmed to have improved the IMRR by about 12 dB.