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On-chip light sensor

  • US 5,481,118 A
  • Filed: 01/26/1995
  • Issued: 01/02/1996
  • Est. Priority Date: 01/08/1993
  • Status: Expired due to Term
First Claim
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1. A circuit for providing an electrical signal to indicate when incident light exceeds or falls below a certain level of brightness, comprising:

  • a photodiode for detecting incident light and generating an input current;

    a first current mirror for receiving and amplifying said input current and delivering the amplified input current to an intermediate node;

    a current source for providing a reference current;

    a second current mirror for receiving and amplifying said reference current and for delivering the amplified reference current to said intermediate node; and

    an inverter for receiving the current from said intermediate node and for changing state at its output when said amplified input current exceeds said amplified reference current.

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