A mixed-signal phase-domain FSK demodulator for BLE single-path low-IF receiver

For Bluetooth Low Energy (BLE) application, this paper presents the design and its measurement results of a mixed-signal phase-domain FSK demodulator in a low-IF receiver. The single-path receiver selects the intermediate frequency (IF) at a half of channel bandwidth specific for BLE frequency assignment. The proposed IF signal processing, unlike the conventional frequency discrimination, is implemented by quantizing analog signals with linear-in-phase thresholds. The mixed-signal IF processor successfully demodulates the received signals under 1-MHz data rate. It requires an SNR of 15.5 dB for a bit error rate of 0.1%. The circuits consume 1.1 mA from a single 1.8-V supply voltage with a 0.18-μm CMOS technology.