A Voltage Doubler Circuit is a type of electronic circuit that allows you to double the input voltage. It is based on the principle of capacitor charging and discharging. Voltage doublers are used in power supply designs and other applications where a higher voltage is required from a lower voltage source.
The basic voltage doubler circuit consists of two diodes, two capacitors, and an input voltage source. Let's take a look at how it works:
Charging Phase: During the charging phase, the input voltage (Vin) is connected to the voltage doubler circuit. The first capacitor (C1) charges to Vin, while the second capacitor (C2) remains discharged.
Vin (+)---|>---- C1 ----|<|----- C2 ----- GND
The diodes (D1 and D2) are oriented such that D1 is forward-biased, allowing current to flow from Vin to C1, while D2 is reverse-biased, preventing current flow to C2.
Discharging Phase: During the discharging phase, the input voltage is disconnected, and the capacitors are connected in series. The voltage across the capacitors adds up, resulting in a doubled output voltage (2 * Vin).
Vin C1 ----|<|----- C2 Vout (+)
The diodes now allow the charged capacitors to be connected in series. The positive terminal of C1 connects to the negative terminal of C2, and the output voltage (Vout) is taken from the remaining two terminals, resulting in the doubled voltage.
It's important to note that in practical circuits, some voltage drop across the diodes is inevitable due to their forward voltage drop (typically around 0.7 volts for silicon diodes). As a result, the output voltage will be approximately 1.4 times the input voltage, minus the diode voltage drop.
Voltage doublers find applications in power supply designs where a higher voltage level is required but the available input voltage is limited. For instance:
Low input voltage power supplies: In battery-operated devices or circuits with low input voltage sources, voltage doublers can be employed to generate higher voltages for specific components or loads.
Charge pumps: Voltage doublers are commonly used in charge pump circuits to generate higher voltages for programming memories, powering displays, or driving certain components.
Compact power supplies: Voltage doublers offer a simple and compact solution to double the voltage without the need for bulky transformers, making them suitable for space-constrained applications.
It's worth mentioning that while voltage doublers have their advantages, they also have limitations, such as limited current output capability and increased complexity for higher voltage multiplication. For higher power applications, other voltage conversion techniques like voltage multipliers or switching power converters may be more suitable.