Radio Frequency Energy Harvesting with Power Conversion Efficiency Tracking

Summary

Technology Description

This technology is a novel multi-stage programmable rectifier that can be calibrated to efficiently receive and rectify an RF input to generate a DC voltage output. Each rectifier stage can include a transistor with a programmable threshold voltage and a switch connected to the transistor. Each rectifier stage can also include an additional transistor that can be connected in series with the first transistor. The plurality of voltages provided at the switch allows the threshold voltage of the first transistor to be adjusted in either a positive or negative position to increase efficiency of the rectifier. A calibration process can be used to identify the position of each switch in the rectifier stages that results in the highest efficiency or rectifier output voltage.

Features & Benefits

  • Lower cost, size, and weight (compared to battery-power)
  • High efficiency under variable conditions

Applications

  • Low voltage wireless sensors
  • Biomedical sensors
  • Programmable rectifiers

Background of Invention

Many powered devices rely upon rectifiers to convert an alternating current (AC) power source to a direct current (DC) power source. In recent years, energy harvesting for low-power devices has emerged as a use for rectifiers. Devices such as implantable biomedical sensors, for example, can be powered by receiving radio frequency (RF) energy and rectifying the RF energy to provide a DC voltage to the sensor. Rectified RF energy can then be used in place of a battery, allowing the size of sensors to be reduced.

Increasing rectifier efficiency in such applications makes more power available for use by a sensor or allows a sensor to operate with less received RF energy. Conventional attempts at increasing rectifier efficiency, however, are limited to fixed operating conditions.

Status

Patented, US Patent No. 9,490,725B2; available for licensing

   

This figure shows one implementation of a battery-less sensor system that harvests RF energy with this technology.

Patent Information:
Tech ID:
OSU-12-69
Contact:
David Dickson
IP & Licensing Manager
Oregon State University
541-737-3450
david.dickson@oregonstate.edu
Inventors:
Lingli Xia
Patrick Chiang
Jiao Cheng
Keywords:
Energy harvesting
low power sensors
RF rectifier
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