Charge-Sharing LDO Regulator for Ripple and Capacitor Size Reduction
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Solution Overview
Problem
Conventional low-dropout (LDO) voltage regulators require large external capacitors, occupying valuable space and causing voltage droops and noise due to abrupt current draws, which affect the functionality of loads and other subsystems.
Innovation Solution
The implementation of a charge-sharing loop voltage regulator, which divides the LDO capacitor into a main and auxiliary capacitor, with the auxiliary capacitor charged to a higher voltage and switched in during active load periods to compensate for load current, reducing ripple and total capacitor size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large external capacitor is used in conventional LDO voltage regulators, then output voltage stability is improved, but board space is occupied and IC pin count increases
Solution Approach 1:
The patent divides the single large output capacitor into multiple smaller capacitors (first capacitor and second capacitor). These segmented capacitors are distributed across different substrates or board locations, reducing the concentration of capacitance in one location while maintaining total capacitance value for voltage stability.
Solution Approach 2:
The patent integrates capacitors at multiple levels: on-chip capacitors within the IC, on-substrate capacitors on the circuit board, and potentially distributed capacitors across different layers or sections. This nested arrangement provides cumulative capacitance without requiring a single large external capacitor.
2Reliability
If a large external capacitor is used in conventional LDO voltage regulators, then output voltage stability is improved, but IC pin count increases
Solution Approach 1:
The patent combines multiple capacitor functions into a distributed network that works together as a unified voltage stabilization system. The first and second capacitors, along with their respective switching elements, are coordinated to provide the same voltage stability function that a single large capacitor would provide, but with fewer external connections required.
Solution Approach 2:
The distributed capacitor network serves multiple functions: voltage stabilization, energy storage, and ripple filtering. The system can dynamically allocate capacitance resources between different functions based on operating conditions, reducing the need for dedicated high-capacitance components.
3Productivity
If abrupt current draw is used to compensate load current, then load current requirement is met, but large ripples are generated at input voltage causing noise
Solution Approach 1:
The patent pre-charges the second capacitor during periods when the load does not require maximum current. This stored energy is then rapidly discharged during high-current demand periods, eliminating the need for abrupt current draws from the input voltage and preventing input voltage ripples and noise.
Solution Approach 2:
The patent implements periodic charging and discharging cycles of the distributed capacitors. The switching elements alternately charge capacitors from the input voltage and discharge them to the load, creating a rhythmical current pattern that smooths input current draw and reduces voltage ripples compared to continuous abrupt draws.
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 solution significantly reduces output voltage ripple and total capacitor size, minimizing abrupt current draws and noise on the input voltage, while maintaining efficient power delivery without significant loss of efficiency.
Implementation Method 1
a first capacitor coupled between a ground voltage and an output of the voltage regulator to a first voltage and a second capacitor coupled to the ground voltage
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
Exemplary embodiments are related to voltage regulators. A device may include a first energy storage element coupled between a ground voltage and an output. The device may also include a second energy storage element coupled to the ground voltage and configured to selectively couple to the output. Further, the device may include a voltage regulator coupled between an input and the second energy storage element.