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Signal holding circuit

  • US 4,198,541 A
  • Filed: 02/07/1978
  • Issued: 04/15/1980
  • Est. Priority Date: 02/08/1977
  • Status: Expired due to Term
First Claim
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1. A signal holding circuit comprising:

  • an audio signal input terminal;

    an audio signal output terminal;

    an emitter follower transistor for introducing an audio signal supplied to said input terminal to said output terminal;

    a constant current source transistor connected to an emitter of said emitter follower transistor for defining an emitter current thereof;

    a control signal input terminal for receiving a control signal;

    control circuit means connected between said control signal input terminal and the base of said emitter follower transistor and said constant current source transistor, and operative to substantially cut off said emitter follower transistor and substantially cut off said constant current source transistor when a control signal is applied to said control signal input terminal; and

    a hold capacitor connected in parallel with said constant current source transistor, said audio signal being supplied to said hold capacitor when said emitter follower transistor is conducting, said hold capacitor functioning to hold an output level at the emitter of said emitter follower transistor to a level at a moment immediately before the cut off of said emitter follower transistor in accordance with the supplied audio signal when said emitter follower transistor is cut off.

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