Switched Capacitor Converter Gate Biasing for Light-Load Leakage
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Solution Overview
Problem
Switched capacitor power converters face efficiency degradation due to significant leakage in power switches, particularly at light loads, which is exacerbated by the high number of power switches and the dynamic nature of power delivery systems.
Innovation Solution
Implementing a control gate voltage management system using pull-up and pull-down charge pumps to minimize switching power by pulling the control gate voltage of power switches to optimized levels (Vcc_cp and Vss_cp) when switched off, and utilizing bootstrap capacitors for dynamic leakage reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of power switches is increased to handle dynamic power delivery, then power delivery capability is improved, but leakage loss increases
Solution Approach 1:
The patent applies preliminary action by proactively pulling the control gate voltage to optimized levels (Vcc_cp and Vss_cp) before the power switches are turned off. This preventive measure ensures that when switches are inactive, their leakage is minimized in advance, rather than reacting to leakage after it occurs. The charge pumps prepare the gate voltages beforehand to establish low-leakage states.
Solution Approach 2:
The patent changes the voltage parameter of the control gate from conventional levels to optimized levels (Vcc_cp and Vss_cp) that are specifically designed to minimize leakage. By adjusting the gate voltage parameter to these non-standard levels, the power switches operate with reduced leakage current while maintaining full power delivery capability when needed.
2Device complexity
If conventional control gate voltage management is used, then device complexity is low, but efficiency at light loads degrades
Solution Approach 1:
The patent introduces charge pumps as intermediary devices between the control logic and the power switches. These charge pumps act as mediators that transform conventional control signals into optimized gate voltages (Vcc_cp and Vss_cp), enabling efficient light-load operation without requiring complex direct control circuitry. The charge pumps bridge the gap between simple control logic and sophisticated voltage management.
3Productivity
If switching frequency is increased to improve power delivery speed, then productivity is improved, but switching power loss increases
Solution Approach 1:
The patent changes the voltage parameter of the control gate to optimized levels that reduce the voltage swing required during switching transitions. By operating at Vcc_cp and Vss_cp instead of conventional voltage levels, the switching transitions require less energy, thereby reducing switching power losses even at high frequencies while maintaining fast power delivery response.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances efficiency at both normal and light loads by reducing leakage, allowing for design freedom to optimize the efficiency curve and improve power delivery efficiency.
Implementation Method 1
a charge pump to increase or decrease a control gate voltage of the power switch from a first level to a second level
Implementation Method 2
utilizing bootstrap capacitors for dynamic leakage reduction
Data Source
AI summary
Embodiments herein relate to a switched capacitor power converter which reduces the leakage current through a power switch when the power switch is turned off. In one aspect, a first charge pump provides a voltage Vcc_cp which is higher than a power supply voltage Vcc, and a second charge pump provides a voltage Vss_cp which is lower than a ground voltage Vss. Transistors are used to couple the first charge pump to the control gate of a p-type power switch and to couple the second charge pump to the control gate of an n-type power switch. In another example implementation, the voltage of the power switch is pulled up or down using a bootstrap capacitor.