Half Wave Rectifier Circuit

Half Wave Rectifier Circuit:

A basic diode Half Wave Rectifier Circuit is shown in Fig. 3-1(a). An alternating input voltage is applied to a single diode connected in series with a load resistor RL. The diode is forward biased during the positive half-cycles of the input waveform, and reverse biased during the negative half-cycles. Substantial current flows through RL only during the positive half-cycles of the input. For the duration of the negative half-cycles, the diode behaves almost as an open switch.

The output voltage waveform developed across RL is a series of positive half-cycles of alternating voltage with intervening very small negative voltage levels produced by the diode reverse saturation current.

Half Wave Rectifier Circuit

When the diode is forward biased [Fig. 3-1(a)1, the voltage drop across it is VF, and the output voltage is (input voltage) – VF. So, the peak output voltage is,

Half Wave Rectifier Circuit

Note that Vpi= 1.414 Vi , where Vi is the rms level of the sinusoidal input voltage.

The diode peak forward current is,

Half Wave Rectifier Circuit

During the negative half-cycle of the input [Fig. 3-1(b)], the reverse-biased diode offers a very high resistance. So, only a very small reverse current (IR) flows, giving an output voltage,

Half Wave Rectifier Circuit

While the diode is reverse biased, the peak voltage of the negative half-cycle of the input is applied to its terminals. Thus, the peak reverse voltage, or peak inverse voltage (PIV), applied to the diode is,

Half Wave Rectifier Circuit

Most Half Wave Rectifier Circuit use a reservoir capacitor at the output terminals to smooth the rectified voltage wave into direct voltage [see Fig. 3-1(c)l. It is important to note that the presence of the reservoir capacitor substantially changes the rectified voltage waveform and affects the diode current and voltage requirements.

Updated: January 29, 2019 — 8:55 pm