Self-Timed Charge Pump With Phase-Shifted Stages for Noise Reduction
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Solution Overview
Problem
Conventional charge pumps generate noise due to sudden changes in supply current, which cannot be sufficiently reduced by existing buffer capacitors.
Innovation Solution
A charge pump design utilizing multiple capacitors and diodes with phase-shifted alternating voltages, generated by a ring oscillator, to distribute current peaks evenly and reduce noise, with a closed-loop configuration for controlling the oscillation frequency based on output voltage or current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a single capacitor is used in the charge pump, then the structure is simple, but supply current peaks are high causing noise
Solution Approach 1:
The single capacitor is segmented into multiple capacitors (first capacitor and second capacitor) that operate in parallel. Each capacitor handles a portion of the charge pumping task, which distributes the supply current peaks and reduces noise. The segmentation is achieved by introducing multiple capacitors with different timing characteristics controlled by the phase shift generator.
Solution Approach 2:
The invention introduces dynamic control through a phase shift generator that adjusts the timing of alternating voltages applied to different capacitors. This dynamic timing adjustment ensures that capacitors are charged at different times, spreading out the supply current demand and reducing peak currents. The phase shifting mechanism provides dynamic optimization of current distribution.
2Object-affected harmful factors
If buffer capacitor is added to reduce supply current peaks, then noise is reduced, but the current peaks are not sufficiently reduced
Solution Approach 1:
Instead of relying solely on a buffer capacitor, the invention segments the charge pumping function across multiple capacitors. Each capacitor contributes to smoothing the supply current by operating with different timing, achieving better current distribution than a single buffer capacitor can provide.
Solution Approach 2:
The invention employs periodic alternating voltages with phase shifts to drive multiple capacitors. This periodic action with varying phases ensures that current peaks from different capacitors do not coincide, providing continuous smoothing effect throughout the operating cycle rather than just buffering during peaks.
3Object-affected harmful factors
If multiple capacitors with phase-shifted voltages are used, then supply current peaks are reduced and noise is reduced, but the device complexity increases
Solution Approach 1:
The phase shift generator is configured to automatically generate the required phase-shifted alternating voltages based on the operating conditions. This self-service mechanism eliminates the need for external complex timing control circuits, as the system generates its own timing signals internally through the phase shift generator's automatic operation.
Solution Approach 2:
The phase shift generator serves multiple functions: it generates alternating voltages, provides phase shifting, and controls the timing of multiple capacitors. This multi-functionality reduces the need for separate control circuits for each capacitor, thereby managing device complexity while achieving the noise reduction benefits of multiple capacitors.
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 reduces supply current peaks and noise propagation, providing a smoother and more stable output voltage with reduced noise and variations.
Implementation Method 1
The alternating voltages may then be phase shifted with respect to each other. In an embodiment, the phase relationship of the alternating voltages is such that rising and the falling edges of the alternating voltage do not coincide.
Implementation Method 2
Each capacitor is coupled with one side to a diode, and each diode is coupled in forward direction to the output node
Implementation Method 3
The charge pump includes a plurality of capacitors and diodes. Each capacitor is coupled with one side to a diode
Data Source
AI summary
With conventional charge pumps, significant noise is present due at least in part to large changes in the supply current. To combat this problem, a charge pump is provided that includes a number of stages. These stages are coupled to receive periodic alternating voltages having a phase shift with respect to each other so that the changes in the supply current are reduced, which reduces noise.