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US 5,008,632 AGranted
Temperature compensated feedback circuit for setting and stabilizing amplifier DC bias points
AssigneeInternational Business Machines Corporation
InventorPhilip H. Sutterlin
Life of this patent
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Abstract
Described is an improved differential amplifier arrangement with a temperature compensated feedback circuit which sets and stabilizes the DC bias point of the amplifier. The circuit averages the two outputs of the amplifier and generates a DC voltage which is compared with a reference voltage to generate a control signal which is amplified and is used to control the bias point of the amplifier.
Claims1
An improved amplifier comprising:
- a differential amplifier stage having differential input devices (Q.sub.1, Q.sub.2) with a pair of differential input terminals for receiving an input signal, a pair of output terminals, interconnected collector terminals, and interconnected emitter terminals;
- a buffer stage, coupled to the pair of output terminals;
- a first circuit means connected in the interconnected collector terminals, said first circuit means averaging signals in said interconnected collector terminals and generating a single-ended signal representative of a DC component in said signals;
- a second circuit means for generating a reference signal (Vref);
- a third circuit means to compensate for temperature and process variations caused by said buffer stage, coupled to the second circuit means;
- an error amplifier coupled to the third circuit means for comparing Vref with the single-ended signal to generate a bias current signal which directly flows through (Q1, Q2) to set the DC operating point of said differential amplifier stage.
3 more elements
Dependencies are inferred from the claim text.