oscillator circuit

[dfox416]

Hi,
I attached a picture of an oscillator circuit. Does anyone know what is it called and how it works? Any input is greatly appreciated.

[T3sl4co1l]

Phase shift oscillator.

Tim

[kg4arn]

phase shift oscillator.  Each RC section can give almost 90 deg of phase shift, so you need 3 to give 180 degrees for sure.  The drain is 180 deg out of phase with the gate.  180 + 180 = 360 and you have oscillation.

[dfox416]

Thanks. I built it in simulation but I can't get it to oscillate. Is there some sort of excitation it needs to start oscillating?

[kg4arn]

build it for real and play with the RC values and it will oscillate.  Sorry can't help you with simulation.  The excitation is thermal noise.
I have built phase shift oscillators with BJTs not FETs but I don't see why it wouldn't just fine.

[dfox416]

I got it working with a BJT but I cannot seem to make it work with a FET. Are there any special considerations for component values that need to be made when using a FET vs a BJT?

[Rerouter]

Not sure if this is still classed as a phase shift oscillator or an LC tank, but it happily works in simulation as a 10Khz Oscillator