Tunable, Asynchronous, and Nanopower Baseband Receiver for Charging and Wakeup of IoT Devices

Abstract

This paper proposes a novel ultra-low power, tunable, and asynchronous baseband architecture for joint radio frequency (RF) wake-up and charging receivers. The designed system switches between the wake-up and charging operations based on the type of the received RF signal. To our knowledge, the proposed system is the first of a kind that introduces multiple power states to reduce the energy consumption by sequentially activating minimal components required for RF wake-up or charging. The fabricated prototype, using off-theshelf components, features a sensitivity of -40 dBm, a bit rate of 500 bps, and a current consumption of 225 nA at a bias voltage of 2.6 V in the listening state. Current consumption is estimated at 3.225 µA and 13.725 µA while processing the preamble and bit sequence, respectively. The address detector is powered OFF during charging to reduce the system's current consumption to 150 nA. Our experimental results show that shutting down the address detector during charging reduces charging time and allows charging from received power levels that are as low as -6 dBm. We demonstrate that, operating the detector with multiple power modes reduces its current consumption and enhances its noise immunity when compared to conventional address detectors with two power modes of operation.

Charging and Wake-Up of IoT Devices using Harvested RF Energy with Near-Zero Power Consumption

“…The developed methodology builds on our extensive experience in the design, implementation, and prototyping of energy harvesting and wake-up circuits. Detailed description of the proposed architectures at the circuit level can be found in previous work [5], [8].…”

“…In this article, we present a general framework for designing and implementing combined RF energy harvesting and wake-up circuits with different address detector design options. Unlike previous work concerned with circuit design and fabrication under specific constraints [5], we describe the general architecture and the main components needed in combined schemes in addition to the technical challenges that should be addressed. We further present the design of a dualpower-mode pulse width detector (PWD) circuit and a multipower-mode pulse width modulation (PWM) detector and compare their performance in terms of current consumption.…”

Precoded Wake-Up Radio Signals in Multiple-Input Multiple-Output Cellular Networks

“…for MR (10) The characteristics of the aforementioned precoders and the combining matrices of MR and ZF are defined in the sequel. The equations of the combining matrices for RZF, S-MMSE and M-MMSE can be found in [11].…”

“…Therefore, the received power from single-antenna transmitters can not be always sufficient to activate the circuitry of targeted devices, which limits the range of the WuR solution and its practical deployment. Furthermore, the false wake-up probability, defined as the probability that the device wakes-up from a signal that is not intended to it, is high [10].…”