Describe the operation of a switched-capacitor charge pump with voltage doubling in AC-DC conversion.
1 Answer
A switched-capacitor charge pump is a type of voltage converter used in electronic circuits to increase or decrease the voltage level. It operates by using a network of capacitors, switches, and diodes to transfer charge from one capacitor to another, effectively creating a higher or lower voltage output than the input voltage.
In the case of voltage doubling in AC-DC conversion, the switched-capacitor charge pump is used to double the voltage of an alternating current (AC) signal to create a direct current (DC) output voltage that is approximately twice the peak value of the AC input voltage.
Here's how a switched-capacitor charge pump with voltage doubling works in AC-DC conversion:
Basic Components:
Capacitors: The charge pump circuit consists of two capacitors, usually referred to as C1 and C2.
Switches: Two sets of switches are used, typically labeled S1, S2, S3, and S4.
Diodes: Two diodes, D1 and D2, are employed to control the flow of current and prevent backflow.
Operation:
The charge pump operates in two phases, alternating between them in sync with the AC input signal.
Phase 1 (Positive Half-Cycle):
During the positive half-cycle of the AC input, S1 and S3 are closed, while S2 and S4 are open.
C1 is connected to the input voltage source during this phase and charges up to the peak value of the input voltage.
C2 is disconnected from the output, which prevents it from discharging.
Phase 2 (Negative Half-Cycle):
During the negative half-cycle of the AC input, S2 and S4 are closed, while S1 and S3 are open.
C1 is disconnected from the input, and C2 is connected to the output.
The charge stored in C1 is transferred to C2, effectively doubling the voltage across C2.
Diodes D1 and D2 ensure that the voltage across C2 does not discharge back into C1.
Output Voltage:
By transferring the charge from C1 to C2 during each AC cycle, the voltage across C2 accumulates and becomes approximately twice the peak value of the AC input voltage. This voltage is then filtered to create a more stable DC output.
Voltage Ripple and Efficiency:
The efficiency of the switched-capacitor charge pump depends on various factors like the switching frequency, component quality, and losses in diodes and switches. Additionally, there might be some voltage ripple due to the switching action and imperfections in the components.
In summary, a switched-capacitor charge pump with voltage doubling is a circuit used to convert AC input voltage into a DC output voltage that is roughly twice the peak value of the AC input. It achieves this by using a combination of capacitors, switches, and diodes to transfer charge from one capacitor to another during different phases of the AC cycle.
In the case of voltage doubling in AC-DC conversion, the switched-capacitor charge pump is used to double the voltage of an alternating current (AC) signal to create a direct current (DC) output voltage that is approximately twice the peak value of the AC input voltage.
Here's how a switched-capacitor charge pump with voltage doubling works in AC-DC conversion:
Basic Components:
Capacitors: The charge pump circuit consists of two capacitors, usually referred to as C1 and C2.
Switches: Two sets of switches are used, typically labeled S1, S2, S3, and S4.
Diodes: Two diodes, D1 and D2, are employed to control the flow of current and prevent backflow.
Operation:
The charge pump operates in two phases, alternating between them in sync with the AC input signal.
Phase 1 (Positive Half-Cycle):
During the positive half-cycle of the AC input, S1 and S3 are closed, while S2 and S4 are open.
C1 is connected to the input voltage source during this phase and charges up to the peak value of the input voltage.
C2 is disconnected from the output, which prevents it from discharging.
Phase 2 (Negative Half-Cycle):
During the negative half-cycle of the AC input, S2 and S4 are closed, while S1 and S3 are open.
C1 is disconnected from the input, and C2 is connected to the output.
The charge stored in C1 is transferred to C2, effectively doubling the voltage across C2.
Diodes D1 and D2 ensure that the voltage across C2 does not discharge back into C1.
Output Voltage:
By transferring the charge from C1 to C2 during each AC cycle, the voltage across C2 accumulates and becomes approximately twice the peak value of the AC input voltage. This voltage is then filtered to create a more stable DC output.
Voltage Ripple and Efficiency:
The efficiency of the switched-capacitor charge pump depends on various factors like the switching frequency, component quality, and losses in diodes and switches. Additionally, there might be some voltage ripple due to the switching action and imperfections in the components.
In summary, a switched-capacitor charge pump with voltage doubling is a circuit used to convert AC input voltage into a DC output voltage that is roughly twice the peak value of the AC input. It achieves this by using a combination of capacitors, switches, and diodes to transfer charge from one capacitor to another during different phases of the AC cycle.