A 40nm-CMOS, 72 µW injection-locked timing reference and 1.8 Mbit/s coordination receiver for wireless sensor networks

A low-power, fully-integrated 40nm-CMOS timing and receiver circuit for wireless sensor networks is presented. The timing circuit locks on a 30 MHz injected signal which is amplitude modulated on a 2.4 GHz wirelessly received carrier. Phase shifts in the injected signal can be detected, which facilitates the possibility to use the circuit as a low-data-rate network coordination receiver. The oscillator circuit is able to lock to a -66 dBm RF signal with a 30 % modulation depth over a +/- 22 % lock range. The receiver data-rate is around 1.8 Mbit/s. The circuit can deliver a stable clock reference over a 0.7 to 1.5 V supply voltage range and a -20 to 100°C temperature range. The total power consumption of the clock reference and the receiver is 72 μW which makes it suitable for ultra-low-power applications such as RF-powered wireless sensor nodes. The injection-locked clock reference as well as the coordination receiver result in a large power savings compared to other, more inaccurate, timing and receiver solutions.