A Mixed-Signal GFSK Demodulator Based on Multithreshold Linear Phase Quantization

An ultralow-power Gaussian frequency-shift keying (GFSK) demodulator with large tolerance for process variations and wide coverage of data rate for low-intermediate-frequency (low-IF) wireless receivers is presented. A novel multithreshold linear phase quantization technique is proposed to improve the demodulator sensitivity and relax the tradeoff between the selection of the IF and the data rate. A dynamic threshold slicer is employed to efficiently overcome the dc drifts caused by the input frequency offset. The demodulator achieves 490-mV input dc offset cancellation, 800-kHz frequency offset tolerance, and data rate coverage from 100 kb/s to 2 Mb/s. The measured signal-to-noise ratio (SNR) is 16.0 dB for a 0.1% bit error rate (BER) and a 0.25 modulation index. The demodulator has been fabricated in a 0.18-mum complimentary metal-oxide-semiconductor process with only 0.14-mm² active area and 450-muA current drawn from a 1.8-V power supply.