A 4-dB NF GPS receiver front-end with AGC and 2-b A/D

A dual-IF GPS receiver front-end integrates all the active circuitry to down-convert, amplify and digitize the 1,575.42 GHz L1 signal. The chip includes 3 dB NF LNA, 38 dB image reject mixer, VCO with integrated LC tank and varactor, PLL synthesizer, 55-dB range AGC with charge-pump control, 2-b A/D, crystal oscillator and TTL-compatible buffers. The receiver noise figure is 4 dB and maximum gain is 120 dB with a power consumption of 49 mA at 3 V supply. The AGC and 2-b A/D offer better SNR and significantly better blocking performance than the commonly used 1-b quantizers.