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Programmable time base circuit with protected internal calibration

  • US 4,897,860 A
  • Filed: 03/02/1988
  • Issued: 01/30/1990
  • Est. Priority Date: 03/02/1988
  • Status: Expired due to Fees
First Claim
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1. A time base circuit provided with internal calibration, comprising:

  • oscillator means for providing an output signal having a predetermined operating frequency;

    programmable counter means for receiving the output of said oscillator means and dividing said operating frequency by a factor of n to provide a reference signal operating at a reference frequency;

    storage means for receiving from an external source the value of n for storage thereof and for interface of the stored value of n with said programmable counter means; and

    inhibit means for inhibiting change of the value of n in said storage means after storage thereof;

    said reference frequency being a calibrated value and determined after measurement of said output signal from said oscillator means, such that said programmable counter means provides an internal calibration capability.

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