The paper describes a novel mixed-mode GFSK demodulator with a frequency offset cancellation circuit as part of a low-IF Bluetooth receiver. The demodulator is fabricated in TSMC 0.35 /spl mu/m standard CMOS process, consumes 3 mA from a 3 V power supply and occupies 0.7mm/sup 2/ of silicon area. For 10/sup -3/ BER as specified in Bluetooth standard, only 16.2 dB input SNR is required. The co-channel interference rejection is about 11 dB. The demodulator is robust to process technology variation, and no calibration is required. It can track and cancel the time-varying local oscillator (LO) frequency offset between transmitter and receiver during the whole reception time.