A GPS receiver with synthesized local oscillator

Abstract

The authors describe an IC design that includes on one chip the RF amplifier, mixer, IF amplifier, VCO (voltage-controlled oscillator), frequency divider, phase/frequency detector, *2 frequency multiplier, and power regulation functions for a Global Positioning System (GPS) receiver. The GPS L-band frequency is amplified and then downconverted to an IF near 60 MHz. A common-emitter amplifier is designed for low noise, stable gain, and a 50- Omega input match. A four-quadrant mixer is used for the downconversion, and the IF amplifier drives a 50- Omega output. The receiver chip downconverts the low-level GPS signals with conversion gain of about 50 dB while processing high-level digital signals. The total downconversion gain was measured to be greater than 45 dB. Low phase noise in the GPS signal is required for the receiver system; measured phase noise at the IF output is about -60 dBc at 10 Hz-from the carrier.<>