1. A rectifier circuit capable of supplying a direct-current output voltage that is two or more times the peak value of the alternating-current voltage.
2. An electronic circuit that converts AC to DC and multiplies the source voltage.

It consists of capacitor/diode pairs, the capacitor stores the source voltage like a charge pump, and the diode rectifies it.

The output voltage is roughly the input voltage times the number of capacitor/diode pairs; for example, a voltage doubler uses two capacitor/diode pairs while a voltage tripler uses three pairs.