A Crystal-Tolerant Fully Integrated Frequency Synthesizer For GPS Receivers: System Perspective

This paper presents the system level design of a frequency synthesizer for dual band GPS receivers that can be easily integrated in wireless phones (mainly GSM mobile phones). For the ease of integration with GSM wireless systems the synthesizer can tolerate most of the common GSM crystals, besides the GPS crystals. The presented synthesizer was designed to target a low IF down conversion receiver with a tolerable IF range of 10% around 4.092 MHz which allows the use of the famous 10/13/26 MHz GSM crystals and all the GPS crystals. The designed frequency synthesizer generates the LO signals for both L1/L2 bands (1.5713 GHz/1.2317 GHz) with an average phase noise of -95 dBc/Hz,consuming 4.0 5mW/4.5 mW for L1/L2 respectively at 1.2V supply.