A switched-capacitor voltage tripler is a circuit used for AC-DC voltage conversion. It takes an alternating current (AC) input voltage and converts it into a direct current (DC) output voltage that is approximately three times the peak value of the input AC voltage. This type of circuit is commonly used in applications where higher DC voltages are required, such as in power supplies and voltage multipliers.
The basic operation of a switched-capacitor voltage tripler involves using a network of capacitors and switches to accumulate charge and build up the output voltage. Here's how it works:
Clock Signal: The circuit operates with a clock signal that alternates between two phases: a charging phase and a discharging phase. The clock signal determines the timing of the switches and capacitors' operation.
Charging Phase: During the charging phase of the clock signal, the switches are configured such that they connect the capacitors in series with the input AC voltage source. The capacitors are charged to the instantaneous peak value of the AC voltage.
Discharging Phase: In the discharging phase of the clock signal, the switches are reconfigured to connect the capacitors in parallel with each other and the output load. The voltage across the capacitors adds up, resulting in an output voltage that is approximately three times the peak value of the input AC voltage.
Voltage Tripling: The key principle behind the voltage tripling action is that during the charging phase, the capacitors accumulate charge based on the peak value of the input AC voltage. Then, during the discharging phase, these charged capacitors are connected in parallel, effectively adding their voltages together. Since there are three capacitors in this arrangement, the output voltage becomes approximately three times the peak input voltage.
Control Logic: The switches' timing is controlled by a clock generator that ensures the correct alternating phases. Proper synchronization of the clock signal is crucial to ensure that the charging and discharging phases occur at the right times.
Voltage Ripple: Like other voltage multiplier circuits, a switched-capacitor voltage tripler may introduce some voltage ripple in the output due to the finite time intervals during which the capacitors are charged and discharged. This ripple can be minimized through careful design and selection of component values.
Overall, the switched-capacitor voltage tripler provides a compact and efficient way to increase the output voltage without the need for bulky transformers or multi-stage rectifier circuits. However, it's worth noting that while this circuit can produce higher voltages, it's not as efficient as more sophisticated voltage conversion techniques for high-power applications.