A GFSK demodulator based on instant phase computation and adaptive multi-threshold quantization

An ultra-low power mixed-signal Gaussian frequency shift keying (GFSK) demodulator for wireless body area networks (WBAN) is introduced. A novel multi-threshold instant phase zero-crossing detector (MIPZCD) which is composed of a 2-stage poly-phase filter (PPF), an instant phase calculator and an adaptive multi-threshold quantizer is proposed to improve the demodulator phase accuracy and data rate. The measured results show that the demodulator achieves the data rate up to 2 Mbps and the input frequency range from 1.6 MHz to 2.5 MHz. The measured signal-to-noise ratio (SNR) for 0.1% bit error rate (BER) with the GFSK signal of 1 Mbps data rate, 2 MHz center frequency, and 160 kHz frequency deviation is 15.8 dB. The demodulator has been implemented in 0.18-¿m CMOS process with only 0.23 mm² active area and 410¿A drain current from a 1.8V power supply.