Output circuit for semiconductor device, semiconductor device having output circuit, and method of adjusting characteristics of output circuit

  • US 7,495,453 B2
  • Filed: 04/12/2007
  • Issued: 02/24/2009
  • Est. Priority Date: 01/19/2005
  • Status: Active Grant
First Claim
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1. An output circuit for a semiconductor device, comprising:

  • a plurality of impedance-adjustable unit buffers connected in common to a data pin, the plurality of unit buffers being divided into at least first and second groups, each unit buffer including a plurality of parallel-connected transistors each individually on/off controlled;

    a first pre-stage circuit that activates one or more unit buffers belonging to the first group;

    a second pre-stage circuit that activates one or more unit buffers belonging to the second group; and

    an output control circuit that independently selects the first and second pre-stage circuits.

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