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 Vpeak 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 Vp of the input Vin appears across the capacitor C1 and thus VD1 = 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 vin and vc1 and thus the output voltage is vout = vin + vc1 = -Vpsinwt – Vpsinwt = -2Vpsinwt = -2vin 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
