I am currently tasked with building a class AB amplifier using double-gate MOSFETs.
Since there isn't much literature available on the MOSFET itself (regarding biasing and actually using the device in terms of modelling equations for the drain current etc.,) I have regretfully resorted to using a circuit from the the tubecad site, it can be found in the first figure attached and amending it to work as I would want it to (using a 12V supply) in Multisim.
The circuit works perfectly when simulated, connected to an 8ohm load, as I've attached in the Multisim image. I've breadboarded the circuit and have had no success in obtaining any kind of output signal from the amplifier.
A large problem in attempting the design of this amplifier, is that the double-gate MOSFET has been manufacteured as a P-Channel MOSFET.
Only N-Channel double-gate MOSFETs exist. The attached link suggests that both N-Channel MOSFETs be used, where one preserves the phase of the input signal, and the other inverts it.
After breadboarding the circuit, I injected a 200mV, 1kHz signal into the amplifier and my output is basically a straight line. I would expect an amplified signal of approximately 1.8, according to my simulation.
Any help would be appreciated in identifying what the probkem could be in the breadboarded circuit, and if it was a feasible solution in attempting the concept for the double-gate MOSFET.