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Access circuit and method for allowing external test voltage to be applied to isolated wells

  • US 7,310,259 B2
  • Filed: 05/23/2006
  • Issued: 12/18/2007
  • Est. Priority Date: 12/29/2003
  • Status: Active Grant
First Claim
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1. A control circuit for applying a select signal to a gate electrode of a pass transistor responsive to an access signal, the transistor having gate-source terminals coupled between first and second terminals, the control circuit comprising:

  • a shunt transistor having a gate terminal and a pair of source-drain terminals coupled between the first terminal and the gate electrode of the pass transistor;

    a control transistor having a gate terminal coupled to receive the access signal, the control transistor having a pair of source-drain terminals coupled between the first terminal and the gate terminal of the shunt transistor;

    a first switching transistor having a gate terminal coupled to receive the access signal, and a pair of source-drain terminals coupled between a supply voltage and the gate terminal of the control transistor; and

    a second switching transistor having a gate terminal coupled to receive a compliment of the access signal, and a pair of source-drain terminals coupled between the supply voltage and the gate terminal of the shunt transistor.

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