amb
Member of the Trade: AMB Laboratories
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Jelle Schrijver, the Szekeres is a simple MOSFET source follower (aka common-drain amplifier). It has no voltage gain and therefore there isn't the classic "feedback" that we speak of. Feedback is usually applied to reduce the voltage gain (at the same time achieve a lowered output impedance, cancel distortion and extend the bandwidth).
If the amp had been a common-source amp, where the output is taken from the drain pin, then there has to be a resistor from the positive rail to the drain pin, and the ratio of resistance between the drain resistor and the source resistor would determine (roughtly) the voltage gain of the amp. This is called "local feedback", and even though it doesn't look like a loop, it has the same effect.
The same thing applies to a BJT-based common-emitter amp. In fact, it is a basic building block of more complex topologies, where there is local feedback at each stage, and often also a global feedback loop spanning multiple stages, from the output back to the input.
If the amp had been a common-source amp, where the output is taken from the drain pin, then there has to be a resistor from the positive rail to the drain pin, and the ratio of resistance between the drain resistor and the source resistor would determine (roughtly) the voltage gain of the amp. This is called "local feedback", and even though it doesn't look like a loop, it has the same effect.
The same thing applies to a BJT-based common-emitter amp. In fact, it is a basic building block of more complex topologies, where there is local feedback at each stage, and often also a global feedback loop spanning multiple stages, from the output back to the input.