A 1.0 V, 5.4 pJ/bit GFSK Demodulator Based on an Injection Locked Ring Oscillator for Low-IF Receivers

Abstract

This paper presents an ultra-low power, low cost demodulator for gaussian frequency shift keying (GFSK) receivers that use low intermediate frequencies (IF). The demodulator employs a direct IF to digital data conversion scheme by using an injection-locked ring oscillator (ILRO) with a 1-bit flip-flop. It consumes $2.7~\mu \text{W}$ from a 1.0 V supply at a data rate of 500 kbps achieving an energy efficiency of 5.4 pJ/bit which is 30 times better than that of the recently presented works. The demodulator also achieves 17.5 dB SNR at 0.1 % BER while operating at the same date rate. The demodulator is implemented in a $0.18~\mu \text{m}$ standard CMOS process and occupies an active area of 0.012 mm2.