A 27-nW Wake-Up Receiver With a Quartz Transformer Matching Network Achieving −71.9-dBm Sensitivity and −46-dB SIR at 0.8% Offset

This work reports the first ultra-low power wake-up receiver (WuRX) to be integrated with a quartz micro-electromechanical systems (MEMS) transformer-based matching network (MN), achieving the best signal-to-interference ratio (SIR) compared to state-of-the-art sub-100 nW receivers. A quartz resonant piezoelectric transformer (PT) was chosen for its high loaded <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Q (~19,000)</i>, enabling large, passive voltage gain – a necessity for low-power radios where active RF amplification consumes too much power. Optimization of the CMOS envelope detector (ED) input impedance and number of ED stages preserves the high <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Q</i> of the preceding MEMS transformer while maintaining a high passive gain of 27 dB and a narrow bandwidth of 2 kHz at 50 MHz. The quartz PT is designed for maximum voltage gain from a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$50~\Omega $ </tex-math></inline-formula> source to the ED input. The 6-stage ED is designed with an input impedance greater than 1 M<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $ </tex-math></inline-formula> and a conversion gain of 264.9 V<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> to maximize sensitivity without de-<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Q</i>ing the transformer. The WuRX is implemented in a 65-nm CMOS process and achieves a sensitivity of −71.9 dBm while consuming just 27 nW. The measured SIR is −46 dB at a 0.8% frequency offset due to the narrowband filtering from the transformer.