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Multi-state EEprom read and write circuits and techniques

  • US 5,163,021 A
  • Filed: 07/22/1991
  • Issued: 11/10/1992
  • Est. Priority Date: 04/13/1989
  • Status: Expired due to Term
First Claim
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1. A circuit for sensing a test current relative to a plurality of predetermined current levels, comprising:

  • a one-to-many current mirror means for reproducing a test current into one or more reproduced currents, said current mirror having a first leg for carrying the test current and a second leg comprising a plurality of branches, such that each branch is associated with a reference current level;

    a first current source at each branch for reproducing a reproduced current therein, said reproduced current being substantially similar to the test current in the first leg;

    a second current source at each branch for providing a reference current having one of the predetermined reference current levels; and

    means for simultaneously detecting in each branch a relatively high or low voltage at a node between first and second current sources, the relatively high or low voltage corresponding to whether the reproduced current similar to the test current provided by the first current source has magnitude greater or less than that of the reference current provided by the second current source.

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