Power MOSFET Bridge Rectifier

The losses in a bridge rectifier can easily become significant when low voltages are being rectified. The voltage drop across the bridge is a good 1.5 V, which is a hefty 25% with an input voltage of 6V. The loss can be reduced by around 50% by using Schottky diodes, but it would naturally be even nicer to reduce it to practically zero. That’s possible with a synchronous rectifier. What that means is using an active switching system instead of a ‘passive’ bridge rectifier.

The principle is simple: whenever the instantaneous value of the input AC voltage is greater than the rectified output voltage, a MOSFET is switched on to allow current to flow from the input to the output. As we want to have a full-wave rectifier, we need four FETs instead of four diodes, just as in a bridge rectifier. R1–R4 form a voltage divider for the rectified voltage, and R5–R8 do the same for the AC input voltage. As soon as the input voltage is a bit higher than the rectified voltage, IC1d switches on MOSFET T3.

Just as in a normal bridge rectifier, the MOSFET diagonally opposite T3 must also be switched on at the same time. That’s taken care of by IC1b. The polarity of the AC voltage is reversed during the next half-wave, so IC1c and IC1a switch on T4 and T1, respectively. As you can see, the voltage dividers are not fully symmetrical. The input voltage is reduced slightly to cause a slight delay in switching on the FETs. That is better than switching them on too soon, which would increase the losses.
[...]
Author: Wolfgang Schubert – Copyright: Elektor Electronics Magazine
http://www.extremecircuits.net/2010/05/Power-MOSFET-Bridge-Rectifier.html

Rectifier by zener diode
The bridge rectifier circuit uses diode 4 the the converter AC to DC, but this circuit uses zener diode as a rectifier instead of diode plain will be current in the direction of the direct bias in the cycle the first current flows through D1 to. to load and then returning the ZD2 cycle, whil ...
Precision half wave rectifier using op-amp
This circuit provides for right half wave rectification of the input signal. The op-amp IC no-NE5535 is Dual High Slew Rate Op-Amp, it is used for main of this circuit. The input signal have two-phase supply are Fist, positive signals is the gain is 0; And second, negative signals is the gain ...
Full wave rectifier with an op amp IC
This circuit acts rectifier the ACV signal.This circuit usually requires two op-amp, but this circuit uses only one op-amp. The work is easy when a positive input into, The D1, D2 will does not work. The output is equal to R2 / (R2 + R3).When V1 is the input signal and R2 = R3 = R, we will ...
Dimmer With A MOSFET BUZ41A
This circuit shows that dimmers intended for use at mains voltage do not always have to contain a triac. Here, a MOSFET (BUZ41A, 500 V/4.5A) in a diode bridge is used to control the voltage across an incandescent bulb with pulse-width modulation (PWM). A useful PWM controller can be found el ...
Bell Alarm
If you use a lamp with a motion sensor for outdoor lighting, the original electrical switch is actually no longer necessary. If you replace the switch with the circuit described here, an acoustical signal will be generated each time the outdoor lamp is switched on. It’s thus somewhere betwee ...