Simple Mosfet Shunt Regulator

[bimo]

I make a simulation of shunt regulator. Current output max. about 300mA. It tested by my friend. He compared with voltage regulator of LM317/337 with op-amp noise reduction and without. But he think, the shunt regulator sound better.

How can improve this design? Any though are welcome.

 

[rayma]

How small can the output capacitor be, and still have a stable response?

 

[bimo]

How small can the output capacitor be, and still have a stable response?

Do you mean C7 and C16?
If you remove C7 and C16, ripple voltage about 600mVpp at 50mAp output.
With C7 and C16, ripple voltage is 30uVpp.