A low energy injection-locked FSK transceiver with frequency-to-amplitude conversion for body sensor applications

An energy-efficient 915MHz FSK transceiver for wireless body sensor network (BSN) applications is implemented in 0.18um CMOS technology with 0.7V supply. A transceiver architecture based on injection-locked frequency divider (ILFD) is proposed for the low energy consumption. In the receiver, through the ILFD in the signal path, the received FSK signal is converted to amplitude-modulated signal which is applied to the following envelope detector. In the transmitter, the ILFD is used as digitally-controlled oscillator (DCO) which replaces the frequency synthesizer to eliminate the crystal oscillator (XO). The receiver and transmitter consume 420uW and 700uW, respectively, at -10dBm output power with a data rate of 5Mb/s, corresponding to energy consumption of 84pJ per received bit and 140pJ per transmitted bit.