A 107 pJ/b TX 260 pJ/b RX Ultralow-Power MEMS-Based Transceiver With Wake-Up in ISM-Bands for IoT Applications
Kai Tang, Chuanshi Yang, Yanshu Guo, Nan Wang, Yao Zhu, Ying Zhang, Eldwin J. Ng, Joshua E.-Y. Lee, Zhongyuan Fang, Wensong Wang, Hanjun Jiang, Chun-Huat Heng, Yuanjin Zheng
Abstract
This article presents an ultralow-power (ULP) microelectromechanical system (MEMS)-based phase-tracking frequency shift keying (FSK) transceiver (TRX) with an embedded envelop detector-based on–off keying (OOK) wake-up receiver (WuRX). The system supports a shared antenna interface of FSK-matched filter for TRX and a matching network for the FSK receiver (RX) and OOK WuRX. To consume less power, the transmitter employs an adaptive fast switching (AFS) technique for FSK/OOK modulator and uses a high-Q MEMS resonator to get frequency stability. In addition, for better interference filtering, the MEMS-based modulator is shared to provide LO in FSK RX as it owns inherent sidelobe suppression. To support higher blocker/interference rejection with relatively low power, MEMS-based FSK-matched filter plus matching network with current-reuse LNA is co-designed to provide additional passive gain. Fabricated in 65-nm CMOS process, the transmitter (TX) generates FSK signals of −11.2 dBm output power at ISM-915 MHz and the data rate is up to 6 Mb/s. At 1 MHz offset, the measured phase noise (PN) is −140.2 and −139.3 dBc/Hz at 926.3 and 932.4 MHz, respectively. By sharing the modulator, the RX exhibits −36.2 dB in-band signal-to-interference ratio (SIR), −77.5 dBm sensitivity at bit error rate (BER) of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{-3}$ </tex-math></inline-formula> working under 2 Mb/s data rate. The TX, FSK RX, and WuRX consume 642 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{W}$ </tex-math></inline-formula> @6 Mb/s, 520 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{W}$ </tex-math></inline-formula> @2 Mb/s, and 86 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{W}$ </tex-math></inline-formula> @200 kb/s, leading to the energy efficiency of 107, 260, and 430 pJ/b, respectively. The proposed TX achieves over <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.5\times $ </tex-math></inline-formula> better energy efficiency than state-of-the-art results and the FSK RX attains the best FoM with the sensitivity of −77.5 dBm, which are well suited for energy-efficient pico-IoT applications.