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Switching circuit

  • US 10,679,823 B2
  • Filed: 01/23/2019
  • Issued: 06/09/2020
  • Est. Priority Date: 02/18/2015
  • Status: Active Grant
First Claim
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1. A method of matching an impedance comprising:

  • coupling an RF input of a matching network to an RF source;

    coupling an RF output of the matching network to a plasma chamber, wherein the matching network comprises at least one electronically variable capacitor (EVC), each EVC comprising discrete capacitors having corresponding switches, the switches configured to switch in and out the discrete capacitors to alter a total capacitance of the EVC, wherein each switch comprises;

    a first terminal operably coupled to the corresponding discrete capacitor;

    a second terminal;

    a switching circuit coupled between the first terminal and the second terminal, the switching circuit comprising;

    a switching transistor;

    a first switching device that, only when switched ON, passes current from the second terminal to a switching transistor second terminal;

    a second switching device that, only when switched ON, passes current from the first terminal to the switching transistor second terminal;

    a third switching device that, only when switched ON, passes current from a switching transistor third terminal to the first terminal; and

    a fourth switching device that, only when switched ON, passes current from the switching transistor third terminal to the second terminal; and

    a tuning inductor coupled parallel to the switching circuit, wherein a value for the tuning inductor enables the tuning inductor to cancel a cumulative parasitic capacitance of the switching circuit;

    matching an impedance by, for at least one of the switches of the at least one EVC, turning the switching transistor ON or OFF to cause the corresponding discrete capacitor to be switched in or out.

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