Multi-Output LDO Regulator Using Single Error Amplifier
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Solution Overview
Problem
Mobile device LDO regulators face challenges in maintaining output voltage accuracy with insufficient dropout voltage, leading to decreased power efficiency and increased chip size due to the need for multiple error amplifiers to provide multiple output voltages.
Innovation Solution
A voltage regulator circuit with a single error amplifier and multiple power transistors, where the error amplifier generates output signals to control the on/off states of power transistors, allowing for efficient regulation of multiple output voltages without increasing the size or driving current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the dropout voltage is increased to prevent errors in the output voltage of the LDO regulator, then the output voltage accuracy is improved, but the power efficiency of the LDO regulator decreases
Solution Approach 1:
The error amplifier is divided into multiple independent amplification units (first amplification unit, second amplification unit, etc.), each capable of providing a specific gain. This segmentation allows the system to achieve high overall gain without requiring a single high-dropout-voltage amplifier, thus maintaining output voltage accuracy while improving power efficiency.
Solution Approach 2:
The system dynamically selects and combines different amplification units based on the required output voltage level. By adaptively adjusting which amplification units are active and their combination, the system achieves accurate voltage regulation across different operating conditions without consistently requiring high dropout voltage, thereby improving overall power efficiency.
2Adaptability or versatility
If a plurality of error amplifiers are used to provide the LDO regulator with a plurality of output voltages, then the ability to provide multiple output voltages is improved, but the size of the chip and driving current increase
Solution Approach 1:
A single error amplifier circuit is designed with multiple amplification units that can be selectively combined to provide different output voltages. This multi-functional design allows one amplifier circuit to replace what would traditionally require multiple separate amplifiers, reducing chip area while maintaining the ability to provide multiple output voltages.
Solution Approach 2:
Multiple amplification units are merged into a single integrated error amplifier circuit, sharing common components such as the input stage and feedback network. This merging reduces the total component count and chip area required compared to using separate amplifiers for each output voltage, while still enabling multiple output voltage capabilities.
3Adaptability or versatility
If a plurality of error amplifiers are used to provide the LDO regulator with a plurality of output voltages, then the ability to provide multiple output voltages is improved, but the driving current increases
Solution Approach 1:
The single error amplifier with multiple amplification units serves multiple output voltage functions, reducing the total number of amplifiers needed. Since each amplification unit can be independently controlled, the system only activates the necessary units for the current operating condition, minimizing the total driving current required compared to having all amplifiers continuously active.
Solution Approach 2:
The system dynamically activates only the required amplification units based on the desired output voltage, rather than continuously powering all amplifiers. This dynamic selection reduces the average driving current consumption while maintaining the capability to provide multiple output voltages when needed.
Data Source
AI summary
A voltage regulator is provided that includes an error amplifier circuit having a reference voltage input port that receives a reference voltage, N input ports, N output ports, and N power transistors, where N is a positive integer that is greater than or equal to 2. Each of the power transistors has a gate that is connected to one of the N output ports. The error amplifier amplifies a difference between the reference voltage and each of N respective feedback voltages input to the N input ports, respectively, and outputs amplified voltages to the respective N output ports.