High voltage operational amplifier output stage
First Claim
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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Accused Products
Abstract
A current sourcing output stage for a high voltage operational amplifier receives a low voltage input signal (VIN) and provides a high current output signal corresponding to the low voltage input signal at an output terminal (8). A first PNP transistor (Q1) is coupled between a voltage supply (VCC) and a plurality of cascaded PNP transistors (Q2, Q3, Q8-Q11) coupled to the output terminal (8). The base of the first PNP transistor (Q1) is coupled to receive the input signal (VIN) and the bases of the cascaded PNP transistors are coupled to receive different bias voltages A control circuit (Q5-Q7, R1-R5) is coupled to the voltage supply (VCC) and has an input coupled to the output terminal (8) for deriving a plurality of bias voltages and to the cascaded PNP transistors (Q2, Q3, Q8-Q11) to supply the bias voltages to the respective bases of the cascaded PNP transistors, so that the cascaded PNP transistors (Q2, Q3, Q8-Q11) are biased by bias voltages dependent on the voltage swing of the output signal.
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Citations
6 Claims
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1. A current sourcing output stage for a high voltage operational amplifier, the output stage comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification