A Micro-Acoustic Enhanced Low-Impedance Antenna System for IoT Wake-Up Receivers

In this work, we propose a passive radio frequency (RF) front-end tailored for wake-up receivers (WuRx) to be deployed in cellular Internet of Things (IoT) devices and wearables networks, featuring a low radiation resistance antenna and a high- $Q$ matching network implemented with microacoustic resonators integrated to obtain a systematic higher node’s sensitivity at no cost in terms of power consumption. We show how these components can be co-designed to obtain high passive voltage gain, hardware-level blocker immunity, and increased resilience to integration parasitics, relaxing link budget for low-power IoT nodes. We report experimental validation of a PCB antenna with 2-dBi gain measured on an 11- $\Omega $ input resistance at resonance, and an in-house fabricated micro-electro-mechanical system (MEMS) thin-film aluminum nitride bulk acoustic resonator with a quality factor $Q=550$ and a piezoelectric coupling coefficient $k_{t}^{2} = \mathrm {7~ \%}$ , hybridly integrated with a commercial off-the-shelf low-power WuRx circuit to benchmark the proposed RF front-end design at 850 MHz. We demonstrate a passive voltage gain of 12 dB due to the MEMS resonator, and an additional 11 dB due to the proposed antenna design (for a total of an unprecedented 2-dB passive gain in this frequency range) leading to an over the air −61-dBm minimum detectable input power and 23-dB blocker rejection.