Ping-Pong Charge Pump Voltage Ripple Reduction
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Solution Overview
Problem
Conventional ping-pong charge pumps face issues with voltage output ripple and snapback due to inadequate equalization times and the use of equalization switches, which can lead to damage and inefficiencies.
Innovation Solution
The implementation of a ping-pong charge pump system that equalizes voltages between flying capacitors using differential control currents, allowing one capacitor to drive the output load while the other is charged, and vice versa, without the need for an equalization switch, thereby extending equalization periods and preventing snapback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an equalization switch is used to equalize capacitor charges, then the ping-pong charge pump can maintain voltage balance between capacitors, but snapback occurs due to high bulk current and parasitic resistance causing damage and reduced reliability
Solution Approach 1:
The patent removes the equalization switch from the circuit entirely. Instead of using a switch to equalize capacitor charges, the system relies on the natural alternating charge and discharge cycles of the flying capacitors to maintain voltage balance, thereby eliminating the source of snapback damage while preserving capacitor voltage balance
Solution Approach 2:
The patent introduces a bulk voltage compensation circuit that acts as an intermediary to counteract the harmful effects of parasitic resistance. The compensation circuit generates a bulk voltage that offsets the voltage drop across the parasitic resistance, preventing snapback without requiring an equalization switch
2Reliability
If an equalization switch is implemented, then capacitor equalization can be achieved, but the implementation area increases due to the additional switch component and associated circuitry
Solution Approach 1:
The patent eliminates the equalization switch and its associated control circuitry, thereby removing the area overhead while maintaining capacitor equalization through the inherent ping-pong operation of the flying capacitors
Solution Approach 2:
The flying capacitors automatically equalize their charges through their natural alternating charge and discharge cycles without requiring external equalization circuitry, making the system self-equalizing and reducing area requirements
3Stability of the object's composition
If the equalization period is extended to reduce output voltage ripple, then voltage smoothness improves, but the time available for charge pumping decreases, reducing overall productivity
Solution Approach 1:
The patent employs periodic clock signals to control the charge and discharge cycles of the flying capacitors. By optimizing the clock frequency and duty cycle, the system achieves both smooth output voltage and high charge pumping efficiency without requiring extended equalization periods
Solution Approach 2:
The patent ensures continuous charge pumping action by overlapping the charge and discharge phases of the flying capacitors. The ping-pong operation allows one capacitor to charge while the other discharges, maintaining continuous power delivery and reducing the need for long equalization periods
Data Source
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AI summary
Systems, apparatuses, and methods provided for ping-pong charge pumps. Flying capacitors present in ping-pong charge pumps are operated out of phase to increase equalization periods. Out-of-phase operation also decreases voltage differences between flying capacitors during equalization periods thus decreasing ping-pong charge pump output voltage ripple and snapback. The voltages of the flying capacitors may be equalized without the use of an equalization switch. Differential control currents that are based on the voltage difference between the flying capacitors are used to enable or disable the flying capacitors from driving an output load of the ping-pong charge pump during certain phases of operation. A capacitor with a lower voltage may be disabled, thus providing for voltage equalization as the enabled capacitor sources current to the output load. The flying capacitors are also equalized during overlapping time periods in which the flying capacitors are charging.