I would work hard to either combine the difference amplifiers with the error amplifiers to reduce each control loop to one stage for easier frequency compensation, or remove the difference amplifiers from inside the control loops.
The only differential amplifier is the voltage sensing amplifier though, i need it to measure actual voltage applied to load, previously my design just used voltage divider which get interfered by voltage drop on current sense resistor.
I think it will be pretty hard to simplify the op amp stage, since my design is actually just a copy from those reference design, but i will try.
5 amps at 20 volts is beyond the power capability of a single 2N3055. There are more powerful parts in the TO-3 and other packages which might be suitable if you do not want to parallel parts.
I will use the pretty beefy 2SC2922 with overclocked AMD fan on processor heatsink, i has tested it and it was able to withstand full 100W of dissipation power for hours without problem.
The drive and output transistors should have base-emitter shunt resistors to improve turn-off performance. At a minimum, the output transistor needs this to prevent runaway from leakage at high temperatures. I would like to see a design where the output transistors are driven by class-AB drivers; diamond buffers could be used.
Ah yes, thank you very much for pointing that out, definitely going to add it in!
As for the output transistor driver, what could be possible improvement acquired by changing to those drivers?
The current sensing arrangement with the sense resistor in series with the output capacitor adds a zero to the frequency response which makes frequency compensation easier if the output capacitor's ESR is too low, but most designs still place the current sense resistor on the high side. If the current limit amplifier is referenced to the output, then no difference amplifier is required inside the control loop.
I'm sorry but i don't really get what you said. Is it basically output capacitor should just be placed on OUT+ and GND, instead of OUT+ and OUT- to improve frequency response?
I use low-side sensing and regular non-inverting amp though, so no differential amplifier on current control loop.