Small-Area Radiofrequency-Energy-Harvesting Integrated Circuits for Powering Wireless Sensor Networks

Abstract

This study presents a radiofrequency (RF)-energy-harvesting integrated circuit (IC) for powering wireless sensor networks with a wireless transmitter with an industrial, scientific, and medical (ISM) of 915 MHz. The proposed IC comprises an RF-direct current (DC) rectifier, an over-voltage protection circuit, a low-power low-dropout (LDO) voltage regulator, and a charger control circuit. In the RF-DC rectifier circuit, a six-stage Dickson voltage multiplier circuit is used to improve the received RF signal to a DC voltage by using native MOS with a small threshold voltage. The over-voltage protection circuit is used to prevent a high-voltage breakdown phenomenon from the RF front-end circuit, particularly for near-field communication. A low-power LDO regulator is designed to provide stable voltage by using zero frequency compensation and a voltage-trimming feedback. Charging current is amplified N times by using a current mirror to rapidly and stably charge a battery in the proposed charger control circuit. The obtained results revealed that the maximum power conversion efficiency of the proposed RF-energy-harvesting IC was 40.56% at an input power of −6 dBm, an output voltage of 1.5 V, and a load of 30 kΩ. A chip area of the RF-energy-harvesting IC was 0.58 × 0.49 mm2, including input/output pads, and power consumption was 42 μW.

LPWAN and Embedded Machine Learning as Enablers for the Next Generation of Wearable Devices

“…This technology leverages the electromagnetic energy of the omnipresent radiocommunication networks, such as WiFi, BT, or cellular solutions. Although the energy conversion rate is still very low, interesting advances are being achieved in this field [ 58 , 59 ].…”

RF-Powered Low-Energy Sensor Nodes for Predictive Maintenance in Electromagnetically Harsh Industrial Environments

“…Finally, circuits for powering wireless sensor networks have been designed making use of commercially available components at the transmitter side in the 915 MHz RFID ultra-high frequency (UHF) band [ 27 ], showing a comparable PCE at −10 dBm, but exploiting a receiving tag which integrates a matching network with an area in excess of 16 cm 2 and a monopole antenna of approximately the same area, which is too large for the specifications and the requirements of our target application. A higher PCE of 45% at −10 dBm is achieved in [ 28 ], however operating at 900 MHz, with much larger antenna size of 80 mm × 30 mm × 1.5 mm.…”

“…In our work, the area of the sensor node, including the antenna, is only 9 cm 2 (3 × 3 cm 2 ) with a thickness of just 4.2 mm, allowing placement in very small cavities, such as inside the engine compartment. It should also be pointed out that neither [ 27 ] nor [ 28 ] include any sensing on the node.…”

Analysis of rectifier stage number and load resistance in an RF energy harvesting circuit

“…The circuit, which can basically respond to low current and voltage, provides achieving high power conversion efficiency and high DC voltage over the output load . In addition to being practical and simple, Dickson rectifier circuits are widely preferred because they are suitable for being developed . Another advantage of the energy harvesting process with Dickson circuits is that it creates a staged‐structure by adding the same rectifier circuit one after the other.…”

“…9,10 In addition to being practical and simple, Dickson rectifier circuits are widely preferred because they are suitable for being developed. 7,11,12 Another advantage of the energy harvesting process with Dickson circuits is that it creates a staged-structure by adding the same rectifier circuit one after the other. Thus, the output voltage on load resistance increases proportionally to the number of layers.…”