LDO Pole Adaptive Control for Stable Phase Margin
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Solution Overview
Problem
Low-dropout (LDO) regulators experience degraded phase margin due to changing pole frequencies as load current varies, leading to instability and reduced load current range, with conventional solutions increasing area consumption or current consumption.
Innovation Solution
Implementing a pole adaptive control mechanism in LDO regulators by adjusting the tail current based on load current, maintaining a consistent frequency distance between main and second poles, thereby stabilizing the phase margin across varying load currents without increasing area or current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional LDO regulator design is used, then the structure is simple and area consumption is low, but the phase margin degrades and stability is reduced when load current varies
Solution Approach 1:
The patent implements a dynamic tail current source that automatically adjusts the tail current based on the load current. When load current increases, the tail current increases proportionally, and when load current decreases, the tail current decreases. This dynamic adjustment maintains the frequency distance between the main pole and second pole across varying load conditions, thereby maintaining phase margin and stability without requiring manual intervention or fixed design parameters.
Solution Approach 2:
The patent employs a feedback mechanism where the tail current source is controlled by the load current. The control circuit monitors the load current and adjusts the tail current accordingly to maintain stable pole frequencies. This feedback loop ensures that the LDO regulator adapts to changing load conditions while maintaining optimal phase margin and stability characteristics.
2Reliability
If pole adaptive control is implemented to maintain phase margin, then stability is improved, but area consumption or current consumption increases
Solution Approach 1:
The patent implements a self-adjusting tail current source that automatically regulates its own current based on the load current without requiring external control signals or additional power. The circuit uses the existing load current to control the tail current, eliminating the need for separate control circuits or additional power sources. This self-service mechanism maintains phase margin while avoiding increased current consumption or area expansion.
Data Source
AI summary
Certain aspects of the present disclosure generally relate to electronic circuits and, more particularly, to a low-dropout (LDO) regulator. The LDO regulator generally includes: an error amplifier; an output transistor coupled to an output of the LDO regulator and having a gate coupled to an output of the error amplifier, at least one first tail transistor coupled to the error amplifier; and a control circuit having an input coupled to the output transistor and at least one output coupled to at least one gate of the at least one first tail transistor.