Output Regulated Charge Pump Ripple Reduction
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Solution Overview
Problem
Existing charge pumps experience excessive ripple effects due to over-driving at output stages, which can be suppressed by increasing the size of low-density metal fringe capacitors, but this is not area-efficient and preferred.
Innovation Solution
An output regulated charge pump with dual feedback loops, including a low drop out (LDO) regulator and a multi-stage charge pump, that adjusts input voltage based on loading conditions to minimize ripple, using a voltage divider, comparator, and current sensing circuit to control the clock driver and produce a variable output voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the size of low-density metal fringe capacitors is increased to suppress ripple, then the ripple effect is reduced, but the area occupied increases
Solution Approach 1:
The patent changes the operating parameters of the charge pump by dynamically adjusting the input voltage to the charge pump stages based on load conditions. The LDO regulator modulates its output voltage (e.g., between 1.8V and 3.3V) to optimize the charge pump operation, reducing excessive charge injection and minimizing output ripple without requiring larger capacitors
Solution Approach 2:
The patent implements a feedback mechanism where the output voltage of the charge pump is monitored and used to control the LDO regulator's operation. This closed-loop control ensures that the charge pump receives the appropriate input voltage to minimize ripple while maintaining efficient operation across varying load conditions
2Device complexity
If a fixed input voltage is provided to the charge pump, then the circuit design is simplified, but the ripple increases under varying load conditions
Solution Approach 1:
The patent introduces dynamic behavior to the previously static input voltage by implementing an LDO regulator that continuously adjusts its output voltage based on instantaneous load conditions. This dynamic voltage adjustment allows the charge pump to operate optimally across varying loads, minimizing ripple while maintaining manageable circuit complexity through the use of standard regulator components
Data Source
AI summary
An output regulated charge pump including a low drop out (LDO) regulator configured to output a variable first output voltage, a multi-stage charge pump configured to receive the variable first output voltage and produce a second output voltage to power a load, a first feedback circuit configured to compare the second output voltage to a reference voltage, and a second feedback circuit configured to measure level of current used by the load, wherein the second feedback circuit outputs a level select signal to the LDO that is configured to vary a level of the first output voltage and reduce charge pump output ripple.