Differential Charge Pump for MEMS Voltage Generation
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Solution Overview
Problem
Charge pumps face limitations in replacing traditional high voltage sources due to parasitics to ground, space requirements, and time to charge, which restrict their applicability despite their ability to generate high voltage outputs from low supply voltages.
Innovation Solution
A charge pump system comprising two independently-controlled series-connected charge pump sections, each producing electrical charges of opposite polarities, which are selectively activated to generate a high voltage output efficiently, minimizing parasitics and space requirements through silicon-on-insulator manufacturing methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If charge pumps are used to generate high voltage output from low supply voltage, then voltage transformation capability is improved, but parasitics to ground increase
Solution Approach 1:
The charge pump system is divided into multiple independent charge pump sections, each generating high voltage with respect to a common low voltage reference. This segmentation allows each section to have controlled parasitic connections to ground, reducing overall parasitic effects while maintaining high voltage generation capability.
Solution Approach 2:
The patent transitions from single-ended high voltage generation to differential high voltage generation. By creating two high voltage outputs with opposite polarities relative to a common reference, the system adds a dimensional aspect (polarity differentiation) that enables cancellation of parasitic effects and reduces ground-referenced parasitics.
2Power
If charge pump elements (pump stages, control circuits, hold capacitor) are added to generate high voltage, then voltage transformation capability is improved, but space required increases
Solution Approach 1:
Multiple charge pump sections share common components including the low voltage reference node and control circuitry. This merging of common elements reduces the total space required compared to having completely separate charge pump circuits for each high voltage output.
Solution Approach 2:
The common low voltage reference node serves multiple functions: it is the reference for both differential outputs, the connection point for multiple charge pump sections, and the basis for control circuit operation. This multi-functionality reduces the need for separate reference circuits for each charge pump section.
3Power
If charge pump stages are activated to charge capacitor to high voltage, then voltage transformation capability is improved, but time to charge increases
Solution Approach 1:
The differential charge pump configuration enables continuous charging of the output capacitor by maintaining active charge transfer through both positive and negative voltage rails simultaneously. This continuous action reduces charging time compared to sequential single-rail charging approaches.
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 system effectively generates high voltage outputs with reduced parasitics and space requirements, enabling efficient and compact operation, and is applicable in micro-electro-mechanical systems (MEMS) devices without the need for high-voltage transistors, reducing wear and minimizing ringing.
Implementation Method 1
a first plurality of series-connected charge-pump stages is connected between a supply voltage node and a first circuit node, wherein the first plurality of charge-pump stages are operable to produce a first electrical charge at the first circuit node, the first electrical charge having a first polarity
Implementation Method 2
Charge pumps are used to generate a desired high voltage output in configurations where the supply voltage is comparatively low
Implementation Method 3
the first plurality of series-connected charge-pump stages and the second plurality of series-connected charge-pump stages are selectively operable to generate a desired electrostatic force between the at least one fixed electrode and the at least one movable electrode
Data Source
AI summary
The present subject matter relates to charge pump devices, systems, and methods in which a first plurality of series-connected charge-pump stages is connected between a supply voltage node and a first circuit node, wherein the first plurality of charge-pump stages are operable to produce a first electrical charge at the first circuit node, the first electrical charge having a first polarity; and a second plurality of series-connected charge-pump stages is connected between the supply voltage node and a second circuit node, wherein the second plurality of charge-pump stages are operable to produce a second electrical charge at the second circuit node, the second electrical charge having a second polarity.