Patent Number: 4,107,619

Constant voltage – constant current high fidelity amplifier

Abstract: A transistor amplifier in which collector to emitter voltages and currents are kept constant, particularly in the power output stages of the amplifying devices for minimizing distortion due to changes in the transistor beta, the essential form of distortion in amplifiers. High fidelity low power output current from a cascoded transistor amplifier is fed through a load to a second, high power, amplifier having constant current and less than unity gain, with an output summed with the output of the first amplifier such that the output of the first low power amplifier is the signal bearing portion and the output of the second amplifier serves as a current bootstrap, increasing the effective impedance of the load as seen by the first amplifier.

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