why common emitter phase shift 180

Hi All,

Is it possible to achieve a 180 phase shift using active FET? if so can you please explain?

Thanks

Bouchy

The method commonly used at lower frequencies is to use an unbypassed source resistor of the same value as the drain load resistor to the power rail. Then capacitively couple the outputs from the source and drain. The values should be many times larger than 1/gm of the transistor.

You will have to do a simulation or breadboard to verify that this works at RF or microwave frequencies.

With these equal value resistors the source voltage is very much like a common collector gain of +1 amplifier. The drain output is a gain of -1 due to the feedback of the source resistor.

This configuration was once used with bipolar transistors (and even earlier with valves/tubes) in audio amplifiers to get the drive for push-pull common emitter (or common cathode) output stages with a transformer coupling to the speaker load.

use the inv