Temperature-Adaptive Regulator Circuit for Phase Margin Stability
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Solution Overview
Problem
Conventional regulator circuits experience oscillation and ringing of the output voltage due to decreased phase margin caused by environmental temperature changes, especially when using MOS transistors with low bias current, leading to instability and noise.
Innovation Solution
The regulator circuit adjusts the bias current of the differential input stage by using a MOS transistor with a high gate width to gate length ratio as a temperature detector, increasing or decreasing the current to maintain a stable phase margin without altering the phase compensator circuit constants, thereby reducing oscillation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the bias current of the error amplifier is reduced to achieve ultra-low power consumption, then power consumption is improved, but the phase margin decreases causing oscillation and instability
Solution Approach 1:
The patent implements dynamic bias current adjustment by introducing a temperature detection circuit that automatically modifies the bias current of the error amplifier based on detected temperature changes. This dynamic adaptation allows the circuit to maintain stability across temperature variations while operating at low quiescent current, resolving the contradiction between low power consumption and circuit stability.
Solution Approach 2:
The patent changes the bias current parameter of the error amplifier in response to temperature variations. By detecting temperature changes and相应ly adjusting the bias current, the system maintains optimal phase margin and stability without requiring high fixed bias current, thus achieving both low power consumption and reliable operation.
2Reliability
If the phase margin is increased by adding compensation components, then circuit stability is improved, but device complexity increases
Solution Approach 1:
The patent employs a self-service mechanism where the temperature detection circuit automatically adjusts the bias current based on temperature conditions without external intervention. This self-regulating approach maintains circuit stability through adaptive biasing rather than complex external compensation networks, reducing overall device complexity while ensuring reliable operation across temperature ranges.
3Reliability
If capacitor elements are switched according to temperature to change phase margin, then oscillation is reduced, but operation instability and noise are generated
Solution Approach 1:
The patent replaces the mechanical switching of capacitor elements with an electronic bias current adjustment mechanism. Instead of physically switching components based on temperature, the system uses temperature-dependent bias current modulation to achieve phase margin adjustment, eliminating the noise and instability associated with capacitor switching while maintaining oscillation suppression.
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 configuration effectively reduces the occurrence of oscillation and ringing of the output voltage across varying temperatures, improving the phase margin and stability of the regulator circuit.
Implementation Method 1
It has been known that the off-state current of a MOS transistor exponentially increases at high temperature.
Data Source
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Figure 3A~3B
AI summary
A regulator circuit includes an output controlling transistor and a controller circuit. The output controlling transistor is connected between a voltage input terminal and an output terminal. The controller circuit includes an error amplifier circuit which controls the output controlling transistor according to an output feedback voltage. The error amplifier circuit includes a differential input stage, an output stage and a current increasing/decreasing circuit. The differential input stage includes input transistors and a current source. The output stage includes a current source and a transistor connected in series with the current source and amplifies a potential at one output node of the differential input stage. The current increasing/decreasing circuit includes an element having a temperature characteristic, and increases or decreases a current of the differential input stage or the current of the output stage according to the temperature characteristic.