Unsure of what configuration this would be.... but take a power Mosfet and split a trifilar output transformer windings between its Source, Drain, and output stage.
What would its gain be? What would its input impedance be? Its kind of a cross between a Source follower and a Common Source.
I am sure this has a name... its like the McIntosh output stages I believe.
Just trying to figure this out.
Thanks!
What would its gain be? What would its input impedance be? Its kind of a cross between a Source follower and a Common Source.
I am sure this has a name... its like the McIntosh output stages I believe.
Just trying to figure this out.
Thanks!
Actually you would create what in tube electronics is called a catodyne phase splitter.
McIntosh called it Unity Coupling; equal loads for plate and cathode.
It is an example of local (cathode) feedback.
Mosfet input impedance is high by definition, but input capacitance can be a factor.
With high load impedance it would have a gain of 2 (1:1+1), but you will not reach that with a lowish loudspeaker load impedance.
McIntosh called it Unity Coupling; equal loads for plate and cathode.
It is an example of local (cathode) feedback.
Mosfet input impedance is high by definition, but input capacitance can be a factor.
With high load impedance it would have a gain of 2 (1:1+1), but you will not reach that with a lowish loudspeaker load impedance.
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Yes so a winding from positive to drain and one from ground to source. The other winding is connected to output or speaker load. If for example I was using a IRFP240 and used a trifilar wound output transformer... Maybe 24vdc and 2A or so bias. What would be the formula to calculate gain? Yes it would be the unity coupling.
Thank you In advance.
I can try drawing it if you would like...
Thank you In advance.
I can try drawing it if you would like...
You can trifilar windig can be done only in push pull version , where the drain winding of one is in bifilar with the sourcd winding of the other. In SE mode you must bifilar wind drain+output and source + output to have the output windings paralleled. If source and drain windings are identical , than you have 50% feedback ratio. The output impedance will be 2/gm.
Instread ,if you use in shunt feedback Schade type, you can get near 100% .
Instread ,if you use in shunt feedback Schade type, you can get near 100% .
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With an ideal transformer with a ratio of 1:1:1, you would basically have a kind of source follower where only half the load current comes from the source, the other half from the drain. Due to the signal swing at the drain, Miller effect will double the effect of the drain-gate capacitance and the effect of the MOSFET's output conductance will double. So I think it will be nearly equivalent to a source follower that gets loaded by the double load impedance, has twice the normal gate-drain capacitance and twice the gds.
If the Source is not straining to pull the load:
Gain from Gate to Source is near unity. Source to load is transformer ratio; you used the words "trifilar" and "unity". Therefore voltage gain from Gate to Load is unity (a hair less).
Same as Mac when you take load at the cathode taps.
Gain from Gate to Source is near unity. Source to load is transformer ratio; you used the words "trifilar" and "unity". Therefore voltage gain from Gate to Load is unity (a hair less).
Same as Mac when you take load at the cathode taps.