Split Rail Charge Pump Divide Ratio
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional charge pumps have a limited maximum divide ratio and require external components, leading to inefficiencies when generating lower voltages, as they waste power when combined with Low Drop-out Regulators.
Innovation Solution
A split rail charge pump with N switched capacitor circuits and storage capacitors, allowing for a maximum divide ratio of 3·2(N-1), which includes a driver controlling the charge pump, flying capacitors, grounding and output switches, and interconnection switches to achieve higher divide ratios with fewer external components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional charge pumps use a limited number of flying capacitors, then the device complexity is reduced, but the maximum divide ratio is limited to N+1
Solution Approach 1:
The charge pump is divided into multiple independent switched capacitor circuits (first, second, third, and fourth circuits), each capable of operating in different modes. This segmentation allows the system to achieve higher divide ratios by combining the outputs of multiple circuits rather than relying on a single large-capacitor configuration, thus resolving the contradiction between device complexity and maximum divide ratio.
2Adaptability or versatility
If conventional charge pumps combine with LDO to generate lower voltages, then the voltage range is extended, but power efficiency deteriorates due to power waste in the LDO
Solution Approach 1:
The charge pump employs dynamic switching between different operational modes (first mode, second mode, third mode, and fourth mode) through control logic that selectively activates different switched capacitor circuits based on the desired output voltage. This dynamic operation allows the system to efficiently generate a wide voltage range without requiring an LDO, as each mode is optimized for specific voltage division ratios, thereby eliminating the power waste associated with LDO operation.
3Adaptability or versatility
If conventional charge pumps use more flying capacitors to increase divide ratio, then the maximum divide ratio increases, but the number of external components increases
Solution Approach 1:
Each switched capacitor circuit is designed to be multi-functional, capable of operating in multiple modes (first mode, second mode, third mode, fourth mode) depending on switching configuration. This universality allows a smaller number of capacitors to achieve higher divide ratios by reconfiguring their connections and roles, eliminating the need for additional external components that would otherwise be required to achieve the same divide ratios in conventional single-mode designs.
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
The solution enables the generation of lower voltages with improved efficiency by increasing the maximum divide ratio, reducing the need for external components and minimizing power wastage, while allowing for flexible operation modes to achieve various divide ratios.
Implementation Method 1
N switched capacitor circuits that are each coupled to an output terminal, wherein N is an integer
Implementation Method 2
a driver; and a charge pump that is controlled by the driver
Data Source
AI summary
Traditionally, charge pumps, which used flying capacitors, were limited to a maximum divide ratio of N+1 (where N is the number of flying capacitors). Here, however, a charge pump has been provided that allows for a dramatically increased divide ratio. Specifically, several switched capacitor circuits (which are controlled by a driver) allow for flying capacitors to be arranged to provide a maximum divide ratio of 3·2(N-1)−1.