A 45 $\mu$ W Injection-Locked FSK Wake-Up Receiver With Frequency-to-Envelope Conversion for Crystal-Less Wireless Body Area Network

A dedicated ultra-low power fully integrated FSK wake-up receiver (WuRx) for wireless body area network (WBAN) is implemented in 0.18 μm CMOS technology with 0.7 V supply voltage. For low power consumption, a body channel communication (BCC) physical layer (PHY) is adopted with an 80 MHz carrier frequency. Moreover, an injection-locking digitally-controlled oscillator (IL-DCO) is used to provide an extraordinary gain and frequency-to-envelope conversion in the simple and power-efficient envelope detection receiver architecture. The IL-DCO plays an important role in amplifying and demodulating the received FSK signal under a tight power budget. Finally, for low system cost without any external components and calibration overhead, a successive approximation register (SAR) auto-calibration algorithm is proposed to promptly calibrate the frequency drift of the IL-DCO. As a result, the fabricated 1 mm ² single-chip WuRX consumes 45 μW with a data rate of 312 kb/s, providing an 80 MHz reference frequency with 0.25% stability within 102 μs calibration time. The proposed WuRX delivers a stable reference clock to the main transceiver for crystal-less WBAN applications.