Amplifier with high gain bandwidth product - has differential input driving high gain and low output impedance stages all containing NMOS FET's

摘要

A current generator supplies the two arms in parallel of a differential input stage. These arms each contains enhancement and depletion mode transistors. One output is used to control the gate of the supply transistor to provide common mode feedback as a function of the output level of the input stage. A level shift circuit between the input stage and a high gain stage comprises a connection from the gate of the supply transistor to the gate of an enhancement mode transistor in parallel with a transistor of which the gate and drain are connected together. This allows reinjection of a signal to reinforce the output and overcome limitations of input stage cut off frequency. A capacitor and the depletion transistors in series provide phase advance coupling from the input stage to the high gain stage. The output impedance is reduced by feedback through transistors in series in a level shift circuit.