Voltage Regulator Variable Impedance LC Resonance Compensation
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Solution Overview
Problem
Voltage regulators face stability issues due to parasitic inductances at the output, which affect stability and bandwidth at high load currents, leading to potential instability and reduced power efficiency.
Innovation Solution
A voltage regulator with an output amplification stage, intermediate amplification stage, and differential amplification stage, along with a variable impedance that adjusts based on load current, modifies the frequency of the intermediate amplification stage's pole to maintain stability, reducing the impact of LC resonance and maintaining power efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the output current is increased to high levels (1A, 1.5A or more), then the bandwidth and gain bandwidth frequency of the voltage regulator increase, but the LC resonance frequency falls within the bandwidth causing stability degradation
Solution Approach 1:
The patent applies dynamics by making the impedance of the intermediate amplification stage adjustable based on load conditions. The impedance is dynamically modified in dependence of the output current to compensate for LC resonance effects. This allows the system to adapt its frequency response characteristics to maintain stability across varying load currents while preserving high bandwidth performance.
Solution Approach 2:
The patent changes the impedance parameter of the intermediate amplification stage to compensate for LC resonance. By modifying the impedance in dependence of the output current, the pole frequency of the intermediate amplification stage is adjusted to maintain adequate phase margin and stability, preventing the LC resonance from degrading system performance at high currents.
2Reliability
If a variable impedance is added to modify the pole frequency for stability compensation, then stability is maintained at high output currents, but device complexity increases
Solution Approach 1:
The patent implements self-service by using the output current itself to control the impedance modification. The impedance of the intermediate amplification stage is adjusted automatically in dependence of the output current level, eliminating the need for external control circuits or additional sensing mechanisms. The system uses its own operating parameters to self-regulate and maintain stability.
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
The solution ensures stability and power efficiency by adjusting the impedance to prevent bandwidth extension caused by LC resonance at high load currents, maintaining stability without significantly increasing quiescent current.
Implementation Method 1
The output capacitor and the parasitic inductance may form an LC circuit with an LC resonance frequency
Data Source
AI summary
A voltage regulator is presented. The output node of the voltage regulator is coupled to an output capacitor via a conductive path that exhibits a parasitic inductance. The voltage regulator has an output amplification stage for deriving the output current at the output node from the input voltage at the input node in dependence of a drive voltage at an intermediate node of the voltage regulator. The voltage regulator has an intermediate amplification stage for providing the drive voltage at the intermediate node based on a differential output voltage. A differential amplification stage determines the differential output voltage in dependence of the output voltage and in dependence of a reference voltage. The voltage regulator has a sensing unit to provide a load indication which is indicative of the output current and a variable impedance coupled to the intermediate node, where the variable impedance is dependent on the load indication.