A 915MHz 97nW Low-Area Wake-Up Receiver with an Envelope-Tracking Mixer Achieving −73.2dBm Sensitivity

This paper presents a 915MHz bit-level duty-cycled (BLDC) wake-up receiver (WuRX) designed for ultra-low-power Internet-of-Things (IoT) systems. Utilizing an envelope-tracking (ET) mixer, the WuRX generates a phase-following (PF) local oscillator (LO) from the incoming radio-frequency (RF) signals. The recovered PF LO has a low duty cycle of about 10% and aligns the peak and valley voltages of the RF signal. As a result, the on-off keying data is accurately downconverted to the baseband with improved gain. Moreover, the high-speed sampling capability of the ET mixer allows the receiver’s front-end to operate at a low duty cycle of 0.024%, significantly lower than other mixer-based BLDC WuRXs. Dynamic baseband amplifiers with pre-charging and auto-zeroing abilities are employed to save area and reduce power consumption. Fabricated in a 65nm CMOS process, the proposed BLDC WuRX achieves a sensitivity of −73.2dBm at a 1kbps data rate, consuming only 97nW and occupying an ultra-low-area of 0.036mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>.