Multi-stage Charge Pump Voltage Boosting
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Solution Overview
Problem
Existing multi-stage charge pumps face challenges in efficiently increasing input voltage to high output levels while managing changing load impedances and maintaining reliability across different operational modes, leading to inefficiencies and potential capacitor stress.
Innovation Solution
A multi-stage charge pump design featuring polysilicon capacitors in initial stages for energy efficiency and space savings, with metal plate capacitors in the final stage to handle higher voltages, and a level shifter and biasing circuit to manage voltage swings and operational modes, allowing for efficient voltage boosting from 5.5-6.5 V to 38-40 V with minimal capacitor stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If polysilicon capacitors are used in initial stages, then energy efficiency and space savings are improved, but voltage handling capability deteriorates
Solution Approach 1:
The charge pump is divided into multiple stages with different capacitor types. Initial stages use polysilicon capacitors for efficiency, while final stages use metal plate capacitors for voltage handling. This segmentation allows each component to operate in its optimal performance range.
Solution Approach 2:
Different capacitor materials are assigned to different stages based on local requirements. Polysilicon capacitors are used where energy efficiency is critical, while metal plate capacitors are used where high voltage handling is required. This local optimization resolves the contradiction between efficiency and voltage capability.
2Reliability
If metal plate capacitors are used in final stage, then voltage handling capability is improved, but die area increases
Solution Approach 1:
Metal plate capacitors are confined to only the final stage where high voltage handling is necessary, rather than using them throughout the entire charge pump. This segmented approach minimizes the total die area while maintaining voltage handling capability where needed.
Solution Approach 2:
Metal plate capacitors are selectively deployed only in the final stage where high voltage stress occurs, while smaller polysilicon capacitors are used in earlier stages. This local quality assignment reduces overall die area while maintaining reliability at critical points.
3Power
If multi-stage configuration is used, then output voltage is improved, but device complexity increases
Solution Approach 1:
The charge pump is segmented into multiple identical or similar stages connected in series. Each stage contributes to the overall voltage multiplication, achieving high output voltage through cumulative effect rather than a single complex stage.
Solution Approach 2:
Multiple charge pump stages are combined in series configuration, where the output of one stage feeds into the next. This merging of simpler stages achieves the complex function of high voltage generation while maintaining modular simplicity.
4Reliability
If capacitor stress is minimized, then reliability is improved, but voltage boosting capability deteriorates
Solution Approach 1:
Capacitor stress is managed by assigning appropriate capacitor types to different stages. Metal plate capacitors handle the highest voltage stress in the final stage, while polysilicon capacitors operate at lower stresses in earlier stages. This local quality assignment maintains reliability while enabling aggressive voltage boosting.
Solution Approach 2:
The voltage boosting function is segmented across multiple stages, distributing the stress on individual capacitors. Each capacitor only needs to handle a portion of the total voltage swing, reducing individual stress while maintaining overall high voltage boosting capability through series combination.
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 design achieves high efficiency and reliability by optimizing capacitor usage across stages, ensuring polysilicon capacitors operate within safe voltage swings in steady state and metal plate capacitors handle turbo mode voltages, reducing die area and power consumption while maintaining high output voltage.
Implementation Method 1
Each of the first, second and third charge pump stages includes a charge pump circuit of a first type that increases an input signal of a respective charge pump circuit by up to a given amount
Implementation Method 2
Each of the first, second, third and fourth charge pump stages excludes metal plate capacitors
Implementation Method 3
a level shifter that swings a level clock signal between a voltage of an output signal of the third charge pump stage and one of an offset voltage and ground
Data Source
AI summary
In described examples, a multi-stage charge pump includes first, second and third charge pump stages connected in series. Each of the first, second and third charge pump stages includes a charge pump circuit of a first type that increases an input signal of a respective charge pump circuit by up to a given amount. The multi-stage charge pump also includes a level shifter that swings a level clock signal between a voltage of an output signal of the third charge pump stage and one of an offset voltage and ground. The multi-stage charge pump further includes a charge pump circuit of a second type that increases the voltage of the output of the third charge pump stage by up to another amount and provides an output and the other amount is set by the level shifter. Also, the multi-stage charge pump includes a charge pump circuit of a third type.