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Restricted capacitor switching

  • US 10,483,090 B2
  • Filed: 07/09/2018
  • Issued: 11/19/2019
  • Est. Priority Date: 07/10/2017
  • Status: Active Grant
First Claim
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1. An impedance matching network, the network comprising:

  • a radio frequency (RF) input configured to operably couple to an RF source;

    an RF output configured to operably couple to a plasma chamber;

    a first electronically variable capacitor (EVC) comprising discrete capacitors configured to be switched in and out to alter a first capacitance of the first EVC;

    a second EVC comprising discrete capacitors configured to be switched in and out to alter a second capacitance of the second EVC; and

    a control circuit operably coupled to the first and second EVCs, the control circuit configured to;

    determine or receive a reflection parameter value at the RF input or the RF output;

    stop the altering of the first capacitance and the second capacitance when the reflection parameter value is at or below a first reflection value;

    cause a limited altering of the first capacitance and the second capacitance to pursue an impedance match when the reflection parameter value is (a) at or above a second reflection value and (b) at or below the third reflection value, the limited altering allowing only a predetermined number of predetermined discrete capacitors to switch in or out; and

    cause an unlimited altering of the first capacitance and the second capacitance to pursue an impedance match when the reflection parameter value is at or above a third reflection value, the unlimited altering allowing any discrete capacitor of the first or second EVC to switch in or out.

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