A Low Energy Injection-Locked FSK Transceiver With Frequency-to-Amplitude Conversion for Body

Abstract

An energy-ef ficient 920 MHz FSK transceiver for wireless body sensor network (BSN) applications is implemented in 0.18 m CMOS technology with 0.7 V supply. A tran sceiver architecture based on injection-locked frequency divider (ILFD) is proposed for the low energy consumption. In the receiver, the ILFD in the signal path converts the recei ved FSK signal to amplitude-modulated signal which is applied to the next envelope detector. In the transmitter, th e ILFD is used as digitally-con- trolled oscillator (DCO) which directly m odulates the FSK signal with digital data. The DCO replaces the frequency synthesizer to eliminate the crystal oscillator (XO), which leads to reduce power consumption and cost. The tran sceiver can detect whether injection locking occurs or not, and calibrates the frequency drift of DCO over temperature var iation thanks to ILFD based architecture. The receiver and tr ansmitter consume 420 Wa n d 700 W, respectively, at 10 dBm output power with a data rate of 5 Mb/s, corresponding to energy consumption of 84 pJ per received bit and 140 pJ per tr ansmitted bit.