A cost effective binary FSK demodulator for low-IF radios

This paper presents a design of low-cost continuous-phase binary frequency-shift keying (CP-BFSK) demodulator. The proposed demodulator does not require a post-detection filter to suppress sum-frequency components, and hence is suitable for a low-IF receiver architecture. Applied to a Bluetooth receiver with 500 kHz low-IF frequency, the demodulator reaches 10/sup -3/ BER for 16.5 dB SNR and 1 Mbps data-rate. Small modulation indices between 0.28 to 0.35 are demonstrated. Using a 0.25-/spl mu/m mixed-signal CMOS process, the demodulator occupies an active area of 0.22 mm/sup 2/. The power consumption is 5 mW from a 2.5 V single supply.