All Fet Circlotron with only one CCS

Submitted by CircloTronAudio on Thu, 05/16/2019 - 14:55

Thanks to Joseph Norman Berry who offered me a schematic for voltage stage :

20190516_JOB_ALL_FET_CIRCLOTRON.png

Like that circuit, it is a fully floating design, by which I mean it is powered only by the two floating supplies. It also uses no cascodes, as none are really needed here for good performance.
The key difference here is the addition of a differential VAS with active tail current source. This uses a local loop to enhance the differential gain of the VAS, such that even a single-ended input will produce a balanced amplifier output.
To ensure proper thermal compensation for the bias, the PMOS control device should be of the same process type as the NMOS output stage devices, and mounted near them.
To be clear, I am offering this for experimental hobby use only.

Circlotron thread on Diyaudio forum

20190516_JOB_ALL_FET_CIRCLOTRON_FFT.png

20190516_JOB_ALL_FET_CIRCLOTRON_THERMAL.png

Ltspice file

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