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High voltage operational amplifier output stage

  • US 5,708,393 A
  • Filed: 06/12/1996
  • Issued: 01/13/1998
  • Est. Priority Date: 06/24/1995
  • Status: Expired due to Fees
First Claim
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1. A current sourcing output stage for a high voltage operational amplifier, the output stage comprising:

  • an input terminal for receiving a low voltage input signal;

    an output terminal for providing a high current output signal corresponding to the low voltage input signal;

    a first PNP transistor coupled between a voltage supply terminal and a plurality of cascaded PNP transistors coupled to the output terminal, the base of the first PNP transistor being coupled to the input terminal and the of the bases of the cascaded PNP transistors being coupled to receive different bias voltages; and

    a control circuit coupled to the voltage supply terminal and having an input coupled to the output terminal for deriving a plurality of bias voltages and to the cascaded PNP transistors to supply the bias voltages to the respective bases of the cascaded PNP transistors, whereby the cascaded PNP transistors are biased by bias voltages dependent on the voltage swing of the output signal.

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