Ultrasonic Wake-Up With Precharged Transducers

Abstract

We present an ultralow-power millimeter-sized ultrasonic wake-up receiver (WuRx) that uses precharged ultrasonic transducers to wirelessly receive wake-up signatures. Our WuRx takes advantage of the low carrier frequency afforded by the low speed of sound to achieve high impedance, and thus high sensitivity, operation in a millimeter-sized form factor. We discuss the system-level considerations that arise from the use of ultrasound as a mode of signature transmission, including the choice of operating frequency and the effect of transducer miniaturization on WuRx sensitivity. We describe the design of the receiver electronics and support our case for ultrasonic wake-up with thorough wireless measurements of error rate and electrical characterization of multiple dice from the same wafer lot. The receiver electronics are fabricated in 65-nm CMOS technology, while the receiver transducer is fabricated by means of a custom in-house process. The receiver achieves a sensitivity of −59.7 dBm at a bit error rate (BER) of 10 −3 with a power consumption of 8 nW and a footprint of 14.5 mm 2 . Our benchmarking shows that the proposed WuRx achieves the lowest system area/aperture of all RF and acoustic WuRxs in the literature (1.45× smaller than the state of the art) while maintaining competitive sensitivity and power consumption.

Ultra Low-Power 2.5µW CMOS Implementation of a Mixed Analog-Digital Wake-Up System Based on Frequency Analysis

“…bat echolocation frequency), has an average power consumption of about 2.5µW with a power supply in 3V , which is more than 12 times lower than the analog implementation proposed in [10]. Moreover, it power consumption is comparable to [6]- [8] but without the constraints of fixed frequencies or a limited frequency range, making it interesting for a more versatile use. Power budget is split between very short power consuming phases and longer ones having a close to zero power consumption :…”

“…[6] is energy efficient (1.8µW ), but its input signal frequency is limited (less than 1kHz). [7], [8] are also really energy efficient, but focused on detection of specific ultra-sonic frequencies (41 kHz and 57 kHz respectively). [9], [10] have a wider input frequency range, but are based on digital or analog discrete circuits making their power consumption higher than previous implementations.…”

Exposure to High-Frequency Sound and Ultrasound in Public Places: Examples from Zurich, Switzerland

“…The investigation of biological chronic and long-term effects of exposing humans to airborn VHFS/US signals need to be intensified since it is foreseeable that the public is going to be exposed to VHFS/US signals in an increasing manner by PAVA systems [1]. This is in addition to new technology such as wireless power transfer to mm-sized nodes enabling long-range wireless charging or signal transmission as part in the next-generation of the Internet of Things infrastructure [22,23].…”

A 1.25 μJ per Measurement Ultrasound Rangefinder System in 65 nm CMOS for Explorations With a Swarm of Sensor Nodes

“…The works in [43], [44], [46] achieve a sensitivity level of around −81 dBm, while consuming more than 1 μW. In [45], the lowest power consumption of 8 nW is reported with an envelope-detector (ED) first topology, where a sensitivity of −59.7 dBm is In this work, by using a mixer-first front-end, the low-conversion gain of the ED is avoided and the sensitivity of the WURX is improved. One should notice that the FoM W u Rx reported in [46] does not include, similarly to the present work, the negligible power overhead of the bias current generation.…”