A 400 MHz 4.5 nW −63.8 dBm sensitivity wake-up receiver employing an active pseudo-balun envelope detector

Abstract

A 402–405 MHz MICS-band wake-up receiver is presented that achieves −63.8 dBm sensitivity at 4.5 nW. High sensitivity at 400 MHz is accomplished via an 18.5 dB passive voltage gain transformer filter loaded by a high input impedance (R in > 30 kΩ), high scaling factor (k ED > 300), 1.8 nW current re-use pseudo-balun envelope detector, while low power is achieved by operating all active circuits, including the re-generative comparator, baseband correlator, and temperature compensated relaxation oscillator in sub-threshold with a single 0.4 V supply. The chip is fabricated using 0.18 μm CMOS SOI process and achieves the highest figure of merit of all direct envelope detection-based wake-up receivers operating above 400 MHz.