A low-power all-digital GFSK demodulator with robust clock data recovery

Abstract

This paper presents an all-digital Gaussian frequency shift keying (GFSK) demodulator with robust clock data recovery (CDR) for low-intermediate-frequency (low-IF) receivers in wireless sensor networks (WSN). The proposed demodulator can detect and adapt to the intermediate frequency of the received signal automatically. In addition, the CDR can tolerate the frequency deviation of the input clock. An implementation of the demodulator with CDR is realized with HJTC 0.18 ¼m CMOS technology. The chip is designed for GFSK signals with a center frequency of 200 kHz, a modulation index of 1 and a data rate of 100 kbps. Experimental results show that the chip consumes 0.53 mA from a 1.8 V power supply, and only a 11 dB input signal to noise ratio (SNR) is required for 10-3 bit error rate (BER). The tolerance range for IF offset is \pm12.5% at 11 dB input SNR, and the CDR can tolerate frequency deviation of the input clock of \pm0.1%.