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Integrated circuit with test signal buses and test control circuits

  • US 5,541,935 A
  • Filed: 05/26/1995
  • Issued: 07/30/1996
  • Est. Priority Date: 05/26/1995
  • Status: Expired due to Term
First Claim
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1. An apparatus including an integrated circuit (IC) with a plurality of test signal buses for use in performing a plurality of internal logic tests, said IC comprising:

  • a plurality of signal terminals for inputting a plurality of input signals and outputting a plurality of output signals;

    a first plurality of logic circuits for inputting a first plurality of logic signals and outputting a second plurality of logic signals;

    a second plurality of logic circuits, coupled to said plurality of signal terminals, for providing a first plurality of internal signals and receiving a second plurality of internal signals;

    a first test signal bus, coupled to a portion of said plurality of signal terminals, for receiving a first plurality of test signals therefrom;

    a first plurality of signal switches, coupled between said first test signal bus and said first plurality of logic circuits, for receiving said first plurality of internal signals and for receiving a first plurality of control signals and in accordance therewith communicating either said first plurality of internal signals or said first plurality of test signals to said first plurality of logic circuits as said first plurality of logic signals;

    a second test signal bus, coupled to another portion of said plurality of signal terminals, for providing a second plurality of test signals thereto; and

    a second plurality of signal switches, coupled between said first plurality of logic circuits and said second test signal bus, for receiving a second plurality of control signals and in accordance therewith communicating said second plurality of logic signals either to said second test signal bus as said second plurality of test signals or to said second plurality of logic circuits as said second plurality of internal signals.

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