Field effect transistor amplifier

TLDR: In this article, 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 circuits, a first voltage source connected to the source electrodes of the first andsecond FET, a resistor connected between the drain electrodes of both the gate electrodes, and an output stage having third and fourth FET with the latter being connected to opposite ends of the resistor so that the voltage across the latter is applied as

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.