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Isolated capacitive power transfer

  • US 9,780,689 B2
  • Filed: 12/07/2015
  • Issued: 10/03/2017
  • Est. Priority Date: 10/21/2015
  • Status: Active Grant
First Claim
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1. An electronic device to provide isolated capacitive power transfer to a low-power load, the electronic device comprising:

  • an inductor connected to a first terminal of a first capacitor to form a series resonance circuit that provides an alternating current (AC) voltage to a low-power load across the first capacitor;

    a switching circuit connected to provide a switched voltage to the series resonance circuit at a sub-harmonic of the resonant frequency of the series resonance circuit;

    a rectifier connected to a second terminal of the first capacitor, the rectifier providing a rectified voltage to the low-power load;

    a feedback circuit connected to change the sub-harmonic at which the switching circuit operates in response to a change in the low-power load; and

    a buck converter connected to provide an input voltage to the switching circuit;

    wherein the feedback circuit receives voltage information across a feedback capacitor that has a smaller capacitance than the first capacitor;

    wherein the feedback circuit is further connected to fine tune the frequency of the switched voltage;

    wherein the feedback circuit is further connected to adjust the input voltage provided by the buck converter;

    wherein the first capacitor is printed on top of a silicon chip containing the electronic device;

    wherein the inductor is an external inductor;

    wherein the electronic device provides power in the range of 15-25 mW at sixty percent efficiency across a functional isolated barrier of 0.5-1 kV.

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