WCDMA/GSM dual mode signal generation for direct conversion receiver

In this paper, we discuss the design of a VCO and the frequency divider for a dual mode direct conversion receiver (WCDMA/GSM), emphasizing the topology which enables a wide tuning range while achieving low phase noise, and accurate quadrature signal generation in a standard digital 0.25/spl mu/m CMOS process. The designed VCO has a 1.06 GHz tuning range with a 4 GHz of center frequency consuming 16.8 mW from 2.25 V of the power supply. The frequency divider consumes 1 mA. Pros and cons of VCO topology are discussed, and the design of the frequency divider on the phase noise of a signal source is investigated.