A tri-mode Compass/GPS/Galileo RF receiver with all-digital automatic gain control loop

A tri-mode RF receiver with all digital automatic gain control (AGC) loop and non-uniform 2-bit analog-to-digital converter (ADC) is designed for the bands of GPS-L1, Galileo-E1 and Compass B1 in 0.18 μm CMOS process. The RF front-end, analog baseband and frequency synthesizer with voltage controlled oscillator (VCO) have been integrated, and there are only few off-chip components including bypass capacitances, matching network and TCXO. For anti-jamming consideration, an all digital AGC loop with relevant variable gain amplifier (VGA) and non-uniform ADC is implemented to suppress interference and avoid saturation of signal chain. While drawing 35 mA current, this receiver achieves a total noise figure of 4 dB and a maximum gain of 105 dB, with a die area of 2.4 × 2.4 mm².