Display Pixel Voltage Regulator With Variable Phase Compensation
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Solution Overview
Problem
Existing voltage regulators for display panels struggle to maintain a constant pixel power supply voltage when load currents change, leading to unstable operation.
Innovation Solution
A voltage regulator design that includes a voltage divider, error amplifier, variable phase compensating circuit, source follower buffer, and pass transistor, which collectively adjust the amplifier output voltage based on load current changes to ensure stable operation across the entire load current range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional voltage regulator is used, then the circuit structure is simple, but the voltage regulator cannot maintain stable operation when load current changes
Solution Approach 1:
The patent implements a variable phase compensating circuit that dynamically adjusts the phase margin according to load current changes. The circuit switches between different compensation configurations (first compensation circuit for light load, second compensation circuit for heavy load) to maintain optimal stability across the entire load range, transforming a static compensation approach into a dynamic one that adapts to varying operating conditions.
Solution Approach 2:
The patent changes the compensation parameters (phase margin, pole locations) based on load current conditions. By switching between different compensation circuits with different RC time constants and impedance characteristics, the system optimizes the feedback loop stability for each load condition, ensuring reliable operation from minimum to maximum load current.
2Adaptability or versatility
If the load current changes, then the voltage regulator must adapt to different current conditions, but the voltage level becomes unstable
Solution Approach 1:
The patent adjusts compensation parameters dynamically based on load current. The variable phase compensating circuit modifies the feedback loop characteristics (pole-zero locations, phase margin) according to the actual load condition, enabling the voltage regulator to maintain stable output voltage across the entire load current range from minimum to maximum.
Solution Approach 2:
The patent employs a feedback mechanism where the load current information is used to control the switching between different compensation circuits. The error amplifier continuously monitors the output voltage and adjusts the control signal to the pass transistor, while the variable phase compensating circuit ensures the feedback loop remains stable under varying load conditions through dynamic parameter adjustment.
3Reliability
If a fixed compensation circuit is used, then the design is simple, but the phase margin cannot be optimized for different load currents
Solution Approach 1:
The patent divides the compensation circuit into multiple segments or configurations (first compensation circuit and second compensation circuit). Each compensation circuit is optimized for specific load current ranges, allowing the system to select the appropriate compensation configuration based on operating conditions. This segmentation enables optimized phase margin for each load scenario without requiring a single complex all-purpose circuit.
Solution Approach 2:
The patent transforms the static fixed compensation circuit into a dynamic variable phase compensating circuit that automatically adapts its configuration based on load current. The circuit switches between different compensation topologies to maintain optimal phase margin across varying operating conditions, making the compensation system as dynamic and adaptive as the load itself.
Data Source
AI summary
A voltage regulator for outputting a pixel power supply voltage supplied to pixels of a display panel includes a voltage divider configured to generate a feedback voltage by dividing the pixel power supply voltage, an error amplifier configured to generate an amplifier output voltage by comparing a reference voltage and the feedback voltage, a variable phase compensating circuit configured to adjust the amplifier output voltage according to a load current, a source follower buffer configured to generate a control voltage by buffering the adjusted amplifier output voltage, and a pass transistor configured to output, as the pixel power supply voltage, an input voltage based on the control voltage.