I found this circuit in a german electronics magazine.
**broken link removed**
The simulation using Proteus Isis is not satisfactory at all. Reducing the circuit to a two way rectifier results are very poor. (High ripple voltage using a 15.000MF capacitor and a load current of 5A.)
Anybody here who built a similar circuit with better results? That circuit would make sense for low input voltages only. At 6V AC-input the output voltage normally drops to 75% using silicon rectifier diodes due to the forward voltage drop of the diodes.
What frequency are you trying to rectify? I calculate about 3V ripple at 50Hz. This is not a problem with the circuit. If you need less ripple, you need more capacitance.
The gates are pulled up to 10V via 100ohms resistors. Decreasing the gate voltage below 10V the output voltage decreases considerably. Transistors used: IRF4905