Simplified design guidelines for dominant pole amplifiers peaked actively by emitter or source followers

摘要

The author discusses active inductance realization using time moment theory to determine the effective dominant zero and dominant pole of the driving point impedance seen at the emitter of a bipolar junction transistor (or source of a MOSFET) operated as a two-terminal circuit element. The analyses produce sufficient conditions for inductance realization, the value of the effective inductance actually realized, and the signal frequency range over which the effective inductance is nominally constant. Complementary benefits of the analyses include circuit design guidelines that eliminate output inductance in emitter and source followers. This latter information is useful when impedance buffering is required to couple amplifier outputs to capacitive loads. These results are interpreted and applied to the design of an actively peaked, broad-banded integrated circuit amplifier.