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Oscillator receiving variable supply voltage depending on substrate voltage detection

  • US 6,137,335 A
  • Filed: 06/03/1999
  • Issued: 10/24/2000
  • Est. Priority Date: 07/29/1996
  • Status: Expired due to Term
First Claim
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1. An oscillator for controlling semiconductor devices comprising:

  • a power supply circuit coupled to a high voltage, a substrate voltage, and a ground voltage, and configured to generate a first voltage at a power supply node when the substrate voltage is above a selected value and to generate a second voltage at the power supply node when the substrate voltage is below the selected value; and

    an odd plurality of oscillator stages for generating an oscillator signal at a selected frequency, each oscillator stage comprising;

    an input node for receiving a control signal which alternates between third and fourth voltage values;

    a first switch, coupled to the power supply node and to the input node, for conducting current when the control signal differs from the supply voltage signal by a first threshold voltage;

    a second switch, coupled to the power supply node and to the input node, for conducting current when the control signal differs from the ground voltage by a second threshold voltage;

    wherein the first and second switches conduct current in a substantially mutually exclusive manner as the control signal varies from the third voltage value to the fourth voltage value.

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