A frequency synthesizer for a 2.4 GHz IEEE 802.15.4/Zigbee compliant transceiver is presented. The VCO has a 15.2% tuning range from 4580-5275 MHz with 135 MHz/V sensitivity. IQ generation for transceiver applications is performed through frequency division at the output of VCO. Frequency dividers employ hybrid circuit styles including CML and TSPC logic. The synthesizer is implemented in TSMC 0.18 ?m CMOS technology. It occupies an area of 0.9 by 0.7 mm2 only and consumes a total of 15mW from supply voltages of 3V, 1.8V and 1.3V.