Voltage Doubler Circuit Operation

A voltage multiplier is a specialized rectifier circuit capable of producing dc output voltage which is theoretically an integer times the AC peak input, for instance, it is possible to get 200 VDC from a 100 V_peak AC source using a voltage doubler, 300 VDC using a voltage tripler or 400 VDC using a voltage quadrupler. In this article, we focus on voltage doubler circuit, demonstrating how it works.

We have two types of voltage doublers:

• Half-wave voltage doubler
• Full-wave voltage doubler

The operation principle we are going to discuss is based on a half-wave voltage doubler.

Operation of a Voltage Doubler Circuit

Let’s consider the following voltage doubler circuit:

The voltage doubler circuit represented above is actually a combination of a clamper circuit also referred to as a DC restorer circuit consisting of the capacitor C₁ and diode D₁ and a peak rectifier consisting of capacitor C₂ and diode D₂.

During the positive half-cycle of the input waveform diode D₁ conducts, the peak value V_p of the input V_in appears across the capacitor C₁ and thus V_D1 = 0. During the negative half-cycle of the input waveform diode, D₂ conducts, capacitor C₂ is charged to a voltage which is the sum of v_in and v_c1 and thus the output voltage is v_out = v_in + v_c1 = -V_psinwt – V_psinwt = -2V_psinwt = -2v_in as illustrated below:

If there is a load connected across C₂, it will discharge a little bit and thus, voltage across it will drop slightly. But it will get recharged in the next half-cycle. By adding more diodes and capacitors to a voltage doubler, you can form voltage triplers and voltage quadruplers.

You may also read:

• Clipper Circuits – Features & Applications
• The Varactor Diode
• PIN Diode – Features & Applications
• Schottky Diode – Features & Applications