11.10: Bridge rectifier
The bridge rectifier is essential in electronics for efficiently converting alternating current (AC) to direct current (DC). Comprised of four diodes configured in a bridge layout, this rectifier effectively processes both the positive and negative halves of the AC waveform, making it superior to half-wave and full-wave center-tapped rectifiers in terms of voltage regulation and output stability.
Operationally, the bridge rectifier allows current flow through two of its diodes during each half-cycle of the AC input. Specifically, during the positive half-cycles, diodes D1 and D2 conduct, allowing current to pass through the load resistor R, while diodes D3 and D4 are reverse-biased and non-conductive. This action reverses during the negative half-cycles, where diodes D3 and D4 conduct and D1 and D2 are reverse-biased. Despite the alternating nature of the input voltage, the current through the load resistor R remains in a single direction, ensuring a steady positive pulsating DC output.
The peak inverse voltage (PIV) required is the diode voltage (VD) subtracted from the source voltage (VS), yielding a value that is approximately half of the full-wave rectifier with a center-tapped transformer. Thus, the bridge rectifier is more efficient and allows a more compact and cost-effective design.
Furthermore, the secondary winding of the transformer in a bridge rectifier circuit requires fewer turns than that of a center-tapped transformer configuration, enhancing its overall efficiency. The performance of a bridge rectifier can also be significantly improved by integrating Schottky diodes, known for their low forward voltage drop and fast recovery time, or by adding a capacitor filter to minimize ripple, thereby producing a higher-quality DC output.
