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

Abstract

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 2Mbps and the input frequency range from 1.6MHz to 2.5MHz. The measured signal-to-noise ratio (SNR) for 0.1% bit error rate (BER) with the GFSK signal of 1Mbps data rate, 2MHz center frequency, and 160kHz frequency deviation is 15.8dB. The demodulator has been implemented in 0.18-μm CMOS process with only 0.23mm2 active area and 410μA drain current from a 1.8V power supply.