A 20 mW 3.24 ${\hbox {mm}}^{2}$ Fully Integrated GPS Radio for Location Based Services

The challenges in the co-existence of a GPS receiver with cellular phones for location based services are addressed in this paper. A fully integrated GPS radio, realized in a 0.18 mum SiGe technology, demonstrates a 1 dB gain desensitization at 1.9 GHz of -8 dBm, a noise figure of 5 dB, with 20 mW power consumption. Chip area is 3.24 mm². The receiver includes a highly selective LNA, key to minimize desensitization and reciprocal mixing due to the large cellphone leakage, a novel quadrature VCO topology capable of directly driving quadrature passive mixer with high swing and low power consumption, complex bandpass filter, variable gain amplifier, automatic gain control, 2-bit quantizer, and a fractional-N sigma-delta-based PLL that can lock to any crystal frequency.