Charge Pump Timing Control for High Frequency Operation
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Solution Overview
Problem
Existing charge pump architectures face limitations in operating frequency due to inefficiencies in charge transfer between flying capacitors, particularly at higher frequencies and varying temperatures, which affects the ability to maintain voltage levels in devices like image sensors.
Innovation Solution
An enhanced timing strategy for the operation of charge pumps, where specific switch pulses are adjusted to allow for parallel operations of selected switch transitions, ensuring non-overlapping charge and discharge periods, and optimizing switch control signals to extend charge pulses and shorten discharge pulses, thereby improving charge transfer efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional sequential switching strategy is used, then charge transfer between flying capacitors is maintained, but operating frequency is limited due to inefficiencies in charge transfer
Solution Approach 1:
The patent applies preliminary action by extending the charge phase duration before discharge begins. The first charge pulse is extended to ensure complete charge transfer to the first flying capacitor before the discharge phase starts. This pre-charging action ensures that when discharge begins, the full charge is available for immediate transfer, improving efficiency at higher frequencies without requiring longer overall cycle times
Solution Approach 2:
The patent implements dynamic switching strategies where pulse widths are adjusted based on operating conditions. The charge and discharge pulse durations are dynamically optimized to match the actual charge transfer rates, which vary with temperature and frequency. This dynamic adjustment allows the system to maintain optimal efficiency across wide operating ranges
2Reliability
If charge pulses are extended to improve charge transfer, then voltage recovery is maintained, but discharge time increases reducing operating frequency
Solution Approach 1:
The patent segments the switching cycle into distinct, non-overlapping charge and discharge phases. By clearly separating these phases with the first charge pulse extending into the discharge phase timing window, the system ensures complete voltage recovery during the charge phase while the discharge phase operates at optimized duration. This segmentation prevents voltage recovery compromise while maintaining high frequency operation
Solution Approach 2:
The patent changes the timing parameters of the switching pulses, specifically extending the charge pulse width while adjusting the discharge pulse width accordingly. This parameter optimization ensures that voltage recovery is complete before discharge begins, while the overall cycle time remains short enough to support high operating frequencies
3Loss of energy
If parallel switch transitions are implemented, then charge transfer efficiency improves, but timing control complexity increases
Solution Approach 1:
The patent uses preliminary action in timing control by generating the first charge pulse to extend into the time window when the discharge pulse would normally begin. This pre-synchronized timing approach ensures that charge completion is verified before discharge starts, improving efficiency while using straightforward pulse generation logic rather than complex real-time coordination
Solution Approach 2:
The patent introduces timing control circuitry that acts as an intermediary between the charge and discharge switch control. This intermediary logic ensures proper sequencing and timing relationships without requiring direct complex interaction between multiple switch control signals. The timing controller coordinates all switch transitions, simplifying the overall control architecture while enabling efficient parallel operations
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
This strategy enables charge pumps to operate at higher frequencies, such as 50 MHz, while maintaining voltage recovery within the required time frames across a wide temperature range, ensuring reliable operation in devices like image sensors.
Implementation Method 1
a first flying capacitor selectively connectable between a voltage source and a reservoir capacitor
Implementation Method 2
a second flying capacitor selectively connectable between a voltage source and a reservoir capacitor
Data Source
AI summary
The method is for controlling a charge pump of the type where two flying capacitors charge and discharge to a reservoir capacitor in sequence. Part of the switching is carried out in parallel, lengthening the charging pulse at the expense of the conventional comparatively long discharge pulse, thus providing operation at higher frequencies than previously possible.