Display Timing Controller Spread Spectrum Clocking for EMI Reduction
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Solution Overview
Problem
The increasing demand for high-resolution and high-picture update rate in display devices leads to significant electromagnetic radiation interference, which compromises the quality of data transmission and poses challenges in reducing electromagnetic interference while maintaining high-quality signal processing.
Innovation Solution
A method of data transmission in display devices that involves monitoring the data rate of pixel packets, synchronizing clocks, and adjusting data rates within blanking times to reduce electromagnetic interference without introducing jitter during active signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the frequency and energy of signals for data transmission are increased to meet high resolution and high picture update rate requirements, then the data transmission quality is improved, but electromagnetic radiation interference becomes serious
Solution Approach 1:
The patent applies spread spectrum clocking technology that periodically varies the clock frequency around a center frequency. By modulating the clock signal with a pseudo-random sequence, the electromagnetic energy is distributed across a wider frequency range over time, reducing peak radiation intensity while maintaining data transmission quality through periodic synchronization.
Solution Approach 2:
The patent changes the frequency parameter of the clock signal dynamically by applying spread spectrum modulation. The clock frequency is varied within a specified range around a center frequency, transforming the electromagnetic radiation characteristics from concentrated high-frequency peaks to distributed lower peak intensities across a broader spectrum.
2Productivity
If data rate is increased to meet high resolution display requirements, then picture quality is improved, but electromagnetic interference increases
Solution Approach 1:
The patent implements periodic frequency variation of the clock signal used for data transmission. By continuously modulating the clock frequency according to a spread spectrum sequence, the system maintains high data rates while distributing electromagnetic energy over time and frequency, reducing interference peaks.
Solution Approach 2:
The patent introduces dynamic frequency adjustment to the previously static clock signal. The clock frequency is made dynamic through spread spectrum modulation, allowing the system to adaptively vary transmission parameters to optimize both data rate and electromagnetic interference characteristics.
3Object-generated harmful factors
If electromagnetic interference is reduced by lowering signal frequency and energy, then electromagnetic radiation interference is reduced, but data transmission quality deteriorates
Solution Approach 1:
The patent converts the harmful concentrated electromagnetic radiation into a beneficial distributed spectrum. By applying spread spectrum modulation, the system transforms peak electromagnetic interference into distributed low-level radiation across a wider bandwidth, while the pseudo-random modulation sequence enables reliable data recovery through correlation processing.
Solution Approach 2:
The patent uses periodic frequency modulation with spread spectrum sequences to redistribute electromagnetic energy. The periodic variation in frequency, while reducing peak radiation intensity, maintains data transmission integrity through the structured nature of the modulation that enables signal recovery.
Data Source
AI summary
A display device includes a timing controller, a transmission line, and a source driver coupled to the timing controller via the transmission line. The source driver monitors a data rate of a pixel packet in an active area of a frame, synchronizes a clock according to the data rate to generate a synchronized clock, and clocks data in the pixel packet using the synchronized clock.