Field effect transistor amplifier
First Claim
1. A field effect transistor amplifier comprising first DC voltage source means, first and second field effect transistors each having gate, source and drain electrodes, a resistor connected between the drain electrodes of said first and second field effect transistors, means connecting the source electrodes of said first and second field effect transistors to said first DC voltage source means, input circuit means for applying to the gate electrodes of said first and second field effect transistors respective signals of the same polarity corresponding to an input signal to be amplified, second DC voltage source means, third and fourth field effect transistors each having gate, source and drain electrodes, the drain electrodes of said third and fourth field effect transistors being connected to said second DC voltage source means, the source electrodes of said third and fourth field effect transistors being connected to each other, an output terminal connected to the connected together source electrodes of said third and fourth field effect transistors, and means for applying the voltage across said resistor as a DC bias voltage to the gate electrodes of said third and fourth field effect transistors.
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Abstract
A field effect transistor amplifier has a signal input circuit which preferably includes an A-class amplifier, a driving stage having first and second FETs driven in the same phase relation by an input signal applied to their gate electrodes from the signal input circuit, a first voltage source connected to the source electrodes of the first and second FETs, a resistor connected between the drain electrodes of the first and second FETs, an output stage having third and fourth FETs with the gate electrodes of the latter being connected to opposite ends of the resistor so that the voltage across the latter is applied as the DC bias voltage for the FETs of the output stage, a second voltage source connected to the drain electrodes of the third and fourth FETs, and an output terminal connected to the source electrodes of the third and fourth electrodes which are connected to each other. At least the FETs of the output stage are triode characteristic FETs and, if the gain of the A-class amplifier in the signal input circuit is insufficient, the FETs of the driving stage are also triode characteristic FETs.
42 Citations
13 Claims
- 1. A field effect transistor amplifier comprising first DC voltage source means, first and second field effect transistors each having gate, source and drain electrodes, a resistor connected between the drain electrodes of said first and second field effect transistors, means connecting the source electrodes of said first and second field effect transistors to said first DC voltage source means, input circuit means for applying to the gate electrodes of said first and second field effect transistors respective signals of the same polarity corresponding to an input signal to be amplified, second DC voltage source means, third and fourth field effect transistors each having gate, source and drain electrodes, the drain electrodes of said third and fourth field effect transistors being connected to said second DC voltage source means, the source electrodes of said third and fourth field effect transistors being connected to each other, an output terminal connected to the connected together source electrodes of said third and fourth field effect transistors, and means for applying the voltage across said resistor as a DC bias voltage to the gate electrodes of said third and fourth field effect transistors.
Specification