A switched-capacitor charge quadrupler is an electronic circuit used for AC-DC conversion, specifically to increase the output voltage level. It's a type of voltage multiplier that utilizes a series of capacitors and switches to achieve its operation. The term "charge quadrupler" refers to its ability to quadruple the input voltage (assuming ideal conditions) over multiple stages of operation.
Here's a simplified explanation of how a switched-capacitor charge quadrupler works in AC-DC conversion:
Basic Principle: The circuit takes in an AC input voltage, which is typically a low-frequency signal. The goal is to convert this AC voltage into a higher DC output voltage. The switched-capacitor charge quadrupler achieves this by using a combination of capacitors, switches, and diodes.
Voltage Multiplication: The circuit employs a cascading arrangement of capacitor banks, each containing a specific number of capacitors. These capacitors are connected in a way that allows them to charge and discharge in a controlled manner.
Switching Action: At specific intervals, the switches within the circuit are activated in a precise sequence. The switching action serves two main purposes: transferring charge from one set of capacitors to another and doubling the voltage across each capacitor set.
Charge Transfer: During the switching phase, the capacitors are connected in series or parallel configurations. When capacitors are connected in series, their voltage adds up, effectively doubling the voltage. Conversely, connecting capacitors in parallel ensures charge transfer between different voltage levels.
Voltage Doubling: By properly timing the switching actions, the circuit effectively doubles the voltage across the capacitors. This process is repeated in multiple stages, each stage doubling the voltage from the previous stage.
Diode Rectification: Diodes are used in conjunction with the capacitors to ensure that the voltage across the capacitors only increases and doesn't discharge back into the input source during the switching process. This diode rectification prevents the circuit from losing the accumulated voltage.
Output Filtering: After multiple stages of voltage doubling, the final stage of the switched-capacitor charge quadrupler produces a significantly higher DC output voltage compared to the input AC voltage. However, the output may still contain some residual AC ripple. Additional filtering components, such as capacitors and inductors, can be added to further smooth out the output voltage.
It's important to note that real-world circuit implementations may involve more complex designs and considerations, including switching timing, component tolerances, efficiency, and practical limitations. While switched-capacitor charge quadruplers are efficient for voltage multiplication, they may not be as suitable for high-power applications due to their inherent limitations in terms of current handling and efficiency.