Multi-Output LDO Regulator with Replica Units for PSRR
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Solution Overview
Problem
Voltage regulators face challenges in achieving high power supply rejection ratio (PSRR) across a wide range of operating frequencies, particularly in systems with devices like crystal oscillators and digitally controlled oscillators, where noise interference can affect supply voltages.
Innovation Solution
A multi-output-level source follower typed replica capless LDO voltage regulator is designed with a core circuit and multiple replica units, utilizing transistors, resistors, and control signals to maintain stable output voltages and enhance PSRR through a feedback loop and resistance control mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single LDO regulator is used to supply multiple oscillators, then the device complexity is reduced, but the PSRR performance deteriorates due to noise kickback affecting supply voltage stability
Solution Approach 1:
The regulator is divided into a core circuit and multiple replica units. Each replica unit is independently controlled to provide regulated voltage to specific oscillators, preventing noise kickback from affecting other units. This segmentation maintains low complexity while improving PSRR through isolated control paths.
Solution Approach 2:
Each replica unit has its own control signal and can be independently optimized for the specific oscillator it supplies. The control signals are locally adjusted based on the frequency and noise characteristics of each oscillator, providing tailored PSRR performance for each load rather than a one-size-fits-all approach.
2Object-affected harmful factors
If high PSRR is achieved across wide frequency range, then noise interference is reduced, but the device complexity increases due to need for multiple control mechanisms
Solution Approach 1:
Multiple replica units are created as copies of the core circuit, each providing the same noise rejection functionality. Instead of creating a complex single circuit that handles all frequencies, simpler replicated units are used, each optimized for its specific frequency range through individual control signals.
Solution Approach 2:
The regulator employs dynamic control signals that can be adjusted in real-time based on the operating frequency and noise characteristics of each oscillator. This dynamic adaptation allows high PSRR across wide frequency ranges without requiring a statically complex circuit design.
3Adaptability or versatility
If multiple output voltages with different levels are provided, then the adaptability is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The replica units provide multi-functionality by being able to output different voltage levels to accommodate different oscillator requirements. Rather than designing separate regulators for different voltage needs, the universal replica unit structure can be configured through control signals to provide various output levels, reducing manufacturing complexity.
Data Source
AI summary
A regulator for providing a plurality of output voltages is provided. The regulator includes a basic unit and a plurality of replica units. The basic unit amplifies an input voltage to obtain a core voltage according to a first control signal. Each of the replica units outputs one of the output voltages according to the input voltage and one of a plurality of second control signals, wherein at least two of the output voltages have different voltage levels. The first control signal is set according to the second control signals, to make the voltage level of the core voltage substantially equal to or less than a maximum voltage level of the output voltages and substantially equal to or greater than a minimum voltage level of the output voltages.