面向物联网应用的超低功耗3阶互调反向散射无源传感系统

黄瑞杨; 武鹏德

doi:10.11999/JEIT250787

面向物联网应用的超低功耗3阶互调反向散射无源传感系统

doi: 10.11999/JEIT250787 cstr: 32379.14.JEIT250787

黄瑞杨,
武鹏德^,

1.
杭州电子科技大学电子信息学院杭州 310018
2.
杭州电子科技大学温州研究院温州市“微纳传感与物联网”重点实验室温州 325038

基金项目: 温州市基础科研项目(G2023073)

详细信息

作者简介:
黄瑞杨：男，硕士生，研究方向为射频无线能量与数据协同传输

武鹏德：男，副教授，硕士生导师，研究方向为天线设计、无线能量与数据协同传输、面向植入设备的超低功耗通信，可穿戴和植入式无线传感技术等

通讯作者:
武鹏德　wupengde@hdu.edu.cn

中图分类号: TN836
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出版历程
- 收稿日期: 2025-08-25
- 修回日期: 2025-11-18
- 录用日期: 2025-12-01
- 网络出版日期: 2025-12-09

Ultra-Low-Power IM3 Backscatter Passive Sensing System for IoT Applications

HUANG Ruiyang,
WU Pengde^,

1.
College of Electronics and Information Engineering, Hangzhou Dianzi University, Hangzhou 310018, China
2.
Wenzhou Key Laboratory of Micro-Nano Sensing and Internet of Things, Wenzhou Institute of Hangzhou Dianzi University, Wenzhou 325038, China

Funds: Basic Scientific Research Project in Wenzhou City (G2023073)

摘要

摘要: 传统反向散射通信无法同步实现射频能量收集与传感信息读出，而基于有源标签的传感信息回传存在较高通信能耗。该文提出一种新颖的3阶互调(IM3)反向散射式无源传感系统，可在不影响射频能量收集效率的前提下实现传感信息低功耗读出。该文研究了整流电路中反向散射IM3产生机制，通过差频嵌入阻抗调控IM3信号转换效率，传感信息控制嵌入阻抗谐振频率变化，将传感信息映射到IM3信号强度凹陷点变化上，查询器通过扫描该凹陷点反演传感信息。实验结果表明，该系统能准确读取传感信息，能量转换效率仅比纯整流模式下降约5个百分点；在1 m无线传输距离下，反向散射IM3信号反演的传感电压与直接测量值误差小于5%，为解决同步能量收集与模拟量读出、低功耗信息传输问题提供了新方法。
- 无源传感 /
- 无线数据和能量协同传输 /
- 射频能量收集 /
- 低功耗 /
- 3阶互调
Abstract: Objective With advances in wireless communication and electronic manufacturing, the Internet of Things (IoT) continues to expand across healthcare, agriculture, logistics, and other sectors. The rapid increase in IoT devices creates significant energy challenges, as billions of units generate substantial cumulative consumption, and battery-powered nodes require recurrent charging that raises operating costs and contributes to electronic waste. Energy-efficient strategies are therefore needed to support sustainable IoT deployment. Current approaches focus on improving energy availability and lowering device power demand. Energy Harvesting (EH) technology enables the collection and storage of solar, thermal, kinetic, and Radio Frequency (RF) energy for Ambient IoT (AmIoT) applications. However, conventional IoT devices, particularly those containing active RF components, often require high power, and limited EH efficiency can constrain real-time sensing transmission. To address these constraints, this work proposes an Intermodulation-Product-Third-Order (IM3) backscatter passive sensing system that enables direct analog sensing transmission while maintaining RF EH efficiency. Methods The IM3 signal is a nonlinear distortion product generated when two fundamental tones pass through nonlinear devices such as transistors and diodes, producing components at 2f₁–f₂ and 2f₂–f₁. The central contribution of this work is the establishment of a controllable functional relationship between sensor information and IM3 signal frequencies, enabling information encoding through IM3 frequency characteristics. The regulatory element is an embedded impedance module designed as a parallel resonant tank composed of resistors, inductors, and capacitors and integrated into the rectifier circuit. Adjusting the tank’s resonant frequency regulates the conversion efficiency from the fundamental tones to IM3 components: when the resonant frequency approaches a target IM3 frequency, a high-impedance load is produced, lowering the conversion efficiency of that specific IM3 component while leaving other IM3 components unchanged. Sensor information modulates the resonant frequency by generating a DC voltage applied to a voltage-controlled varactor. By mapping sensor information to impedance states, impedance states to IM3 conversion efficiency, and IM3 frequency features back to sensor information, passive sensing is achieved. Results and Discussions A rectifying transmitter operating in the UHF 900 MHz band is designed and fabricated (Fig. 8). One signal source is fixed at 910.5 MHz, and the other scans 917～920 MHz, generating IM3 components in the 923.5～929.5 MHz range. Both sources provide an output power of 0 dBm, and the transmitted sensor information is expressed as a DC voltage. Experimental measurements show a power trough in the backscattered IM3 spectrum; as the DC voltage varies from 0 to 5 V, the trough position shifts accordingly (Fig. 9), with more than 10 dB attenuation across the range, giving adequate resolution determined by the varactor diode’s capacitance ratio. The embedded impedance module shows minimal effect on RF-to-DC efficiency (Fig. 10): at a fixed DC voltage, efficiency decreases by approximately 5 basis points at the modulation frequency, independent of input power, and under fixed input power, different sampled voltages cause about 5 basis points of efficiency reduction at different frequencies. These results confirm that the rectifier circuit maintains stable efficiency and meets low-power data transmission requirements. Conclusions This paper proposes a passive sensing system based on backscattered IM3 signals that enables simultaneous efficient RF EH and sensing readout. The regulation mechanism between the difference-frequency embedded impedance module and backscattered IM3 intensity is demonstrated. Driven by sensing information, the module links the sensed quantity to IM3 intensity to realize passive readout. Experimental results show that the embedded impedance reduces the target-frequency IM3 component by more than 10 dB, and the RF-to-DC efficiency decreases by only 5 percentage points during readout. Tests in a microwave anechoic chamber indicate that the error between the IM3-derived bias voltage and the measured value remains within 5%, confirming stable operation. The system addresses the energy-information transmission constraint and supports battery-free communication for passive sensor nodes. It extends device lifespan and reduces maintenance costs in Ultra-Low-Power scenarios such as wireless sensor networks and implantable medical devices, offering strong engineering relevance.
- Passive sensing /
- Simultaneous Wireless Information and Power Transfer (SWIPT) /
- Radio Frequency (RF) Energy Harvesting (EH) /
- Low-power /
- the Third Order Intermodulation (IM3)

HTML全文

图 1 RF WPT系统概况

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图 2 本文提出的基于IM3信号无源传感系统传感端模型

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图 3 系统传感端中IM3信号分量的产生过程

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图 4 辅助过程中第2次频率转换的交流等效模型

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图 5 本文提出的基于IM3信号无源传感系统的传感端电路原理图

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图 6 嵌入阻抗在差频$ {\omega }_{\Delta } $处的等效模型

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图 7 嵌入阻抗$ {Z}_{{{\omega }_{\Delta }}}\left(V\right) $随差分频率$ {\omega }_{\Delta } $的变化情况

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图 8 电路测试实验环境

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图 9 本文设计的基于IM3信号无源传感系统传感端在不同偏置电压下的反向散射的IM3信号强度变化情况

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图 10 不同输入功率与偏置电压情况下传感信息读出对RF-DC效率的影响

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图 11 空间测试实验环境

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图 12 空间测试实验结果

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表 1 $ {Z}_{{{\omega }_{\Delta }}}\left(V\right) $与反向散射的IM3信号强度关系的仿真结果(两输入信号功率均为0 dBm)

光标	二极管上的基波电压 (V)	嵌入阻抗$ {Z}_{{{\omega }_{\Delta }}}\left(V\right) $ (Ω)	$ {V}_{\text{j,}{{\omega }_{\Delta }}} $ (V)	$ {I}_{\text{IM3,MC}}+{I}_{\text{IM3,AC}} $ (10^–5A)
M1	$ \begin{matrix}{\omega }_{1}=1.11\angle -0.78{^{\circ}}\\ {\omega }_{2}=1.11\angle 0.12{^{\circ}}\\ \end{matrix} $	$ 4.87+\mathrm{j}49.13 $	$ 0.03\angle -78.33{^{\circ}} $	$ 4.52\angle -135.45{^{\circ}} $
M2(谐振点)		$ 500 $	$ 0.40\angle -0.97{^{\circ}} $	$ 0.21\angle -116.17{^{\circ}} $
M3		$ 70.91-\mathrm{j}174.43 $	$ 0.09\angle -18.44{^{\circ}} $	$ 3.98\angle -132.66{^{\circ}} $

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