A compact carrier generation system enabling proper interoperability among quad-band GSM, WCDMA (FDD and TDD) and WLAN (802.11a/b/g) standard is developed. The implementation is achieved in 0.25μm BiCMOS-SiGe process. The measured tuning range is higher than 1GHz (3.05GHz to 4.1 GHz) exceeding by 25% the specifications. The VCO exhibits a phase noise of -118 and -125 dBc/Hz measured respectively at 400KHz and 1MHz offsets while drawing only 2.5 mA from 2.5 V supply. The measured phase noise at 400 KHz offset from the PCS 1900/DCS1800 and the GSM850/900 carriers are respectively -124 dBc/Hz and -130dBc/Hz.