Sampling and Holding Circuit for Reference Voltage Noise Isolation
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Solution Overview
Problem
In LCD controller LSI systems, power supply noise from one reference voltage generation circuit can cause fluctuations in the reference voltage supplied to other circuits, leading to disordered display states and deteriorated touch detection accuracy, especially when power supply fluctuations occur asynchronously with display timing.
Innovation Solution
A sampling and holding circuit is implemented to control the reference voltage, instructing sampling operations when power supply noise is within a predetermined range and holding operations when it exceeds this range, ensuring continuous stable voltage supply to multiple circuit units and reducing the need for individual reference voltage generation circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single reference voltage generation circuit is shared by multiple circuit units, then the number of reference voltage generation circuits is reduced, but power supply noise causes reference voltage fluctuations that deteriorate display quality and touch detection accuracy
Solution Approach 1:
The patent divides the reference voltage supply system into multiple independent reference voltage generation circuits, each serving specific circuit units. This segmentation isolates the impact of power supply noise to individual circuits, preventing noise propagation across the entire system while maintaining multiple reference voltage sources for different functional blocks.
Solution Approach 2:
The patent introduces power supply noise detection circuits as intermediary components that monitor the reference voltage generation circuits. These detection circuits identify noise conditions and trigger switching mechanisms to isolate affected circuits, acting as a mediator between the reference voltage generation circuits and the affected functional blocks to prevent noise propagation.
2Reliability
If individual reference voltage generation circuits are provided for each circuit unit, then reference voltage stability is maintained, but the number of reference voltage generation circuits and trimming circuits increases
Solution Approach 1:
The patent creates reference voltage generation circuits that serve multiple functions: they generate reference voltages for their designated circuit units and simultaneously act as noise isolation barriers. Each reference voltage generation circuit is designed to be universally applicable to different functional blocks, reducing the overall number of circuits needed while maintaining stability.
Solution Approach 2:
The patent merges the reference voltage generation function with noise detection and isolation capabilities into integrated circuit blocks. By combining multiple functions into unified reference voltage generation circuits, the system reduces the total component count while maintaining the stability benefits of having dedicated reference voltage sources for different circuit units.
3Reliability
If power supply noise detection and switching control is implemented, then reference voltage fluctuations are suppressed, but the control circuit complexity increases
Solution Approach 1:
The patent implements power supply noise detection circuits that continuously monitor reference voltage generation circuits in advance, detecting noise conditions before they affect the functional blocks. This preliminary detection enables proactive switching to alternative reference voltage sources, preventing noise propagation rather than reacting after damage occurs.
Solution Approach 2:
The patent establishes feedback loops where power supply noise detection circuits monitor the output of reference voltage generation circuits and feed this information back to switching control circuits. This feedback mechanism enables automatic adjustment and isolation of noisy circuits, maintaining reference voltage stability through continuous monitoring and dynamic reconfiguration.
Data Source
AI summary
In a semiconductor device in which a reference voltage is generated by a reference voltage generation circuit, and the same reference voltage generated is used in a plurality of circuit units for the purpose of generating a voltage, a sampling and holding circuit of the reference voltage is provided in order to provide a standard voltage to the circuit units. A sampling and holding control circuit that controls the sampling and holding circuit instructs the sampling and holding circuit to perform a sampling operation of the reference voltage in case that the semiconductor device operates in a state where power supply noise of the reference voltage generation circuit falls within a predetermined range, and instructs the sampling and holding circuit to perform a holding operation of the reference voltage in case that the semiconductor device operates in a state where the power supply noise exceeds the predetermined range.