HDMI Cable Startup Circuit for Signal Skew Compensation
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Solution Overview
Problem
High-speed differential signaling cables, such as those used for HDMI, suffer from bandwidth limitations and differential skew, leading to signal distortion and attenuation, which existing solutions like passive equalizers cannot adequately address due to random variations in cable characteristics and the lack of sufficient power for embedded active devices.
Innovation Solution
A startup circuit is embedded in the cable to harvest power from differential signals and auxiliary control lines, using a power harvesting driver, voltage raiser, and bootstrapping circuit to provide a predetermined voltage, enabling active signal processing and compensation for signal skew and bandwidth limitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If passive equalizers are used to compensate for signal distortion, then signal quality improves slightly, but they cannot adequately address random variations in cable characteristics and bandwidth limitations
Solution Approach 1:
The patent implements dynamic equalization by adjusting equalizer coefficients in real-time based on detected cable characteristics. The system continuously monitors signal quality and adapts the equalization parameters to compensate for variations in cable length, bandwidth limitations, and differential skew, transforming a static passive equalizer into a dynamic active system that can adapt to changing cable conditions.
Solution Approach 2:
The patent employs feedback mechanisms where the receiver detects signal characteristics and sends information back to adjust the equalization settings. The system uses feedback from signal quality measurements to dynamically modify equalizer coefficients, enabling continuous optimization of signal compensation for the specific cable characteristics being experienced.
2Adaptability or versatility
If active devices are embedded in the cable for signal processing, then signal compensation capability improves, but sufficient power is not available for such embedded active devices
Solution Approach 1:
The patent makes the existing signal lines serve multiple functions: they carry both data signals and power for embedded active devices. By utilizing the differential signal lines for both signaling and power delivery, the system enables active signal processing capabilities without requiring separate power infrastructure, thus resolving the power availability constraint.
Solution Approach 2:
The system enables self-powered operation where the embedded active devices harvest power from the signal lines themselves. The differential signal lines provide both their primary function of carrying data and the secondary function of supplying power to embedded processing elements, allowing the system to serve itself without external power sources.
3Length of stationary object
If cable length is increased to extend reach, then transmission distance improves, but bandwidth decreases and signal attenuation increases
Solution Approach 1:
The patent applies preliminary equalization by pre-calculating and applying equalization coefficients before signal transmission through long cables. The system detects cable characteristics and applies compensatory equalization in advance to counteract the bandwidth limitations and attenuation that will occur over the extended transmission distance, thereby maintaining signal integrity.
Solution Approach 2:
The patent dynamically changes equalization parameters based on detected cable characteristics. By adjusting equalizer coefficients according to the specific cable's bandwidth limitations and length, the system optimizes signal compensation for long-distance transmission, transforming the fixed cable characteristics into adaptable parameters that maintain performance.
4Measurement precision
If differential skew compensation is implemented, then signal accuracy improves, but additional active processing is required which needs power
Solution Approach 1:
The patent makes the signal lines serve dual purposes: carrying data and providing power for differential skew compensation processing. By utilizing the existing differential signal lines to power the active skew compensation circuitry, the system enables high-precision signal accuracy without requiring separate power infrastructure.
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 effectively compensates for signal skew and bandwidth limitations, improving signal quality by providing the necessary power for active signal processing within the cable, enhancing the reliability and performance of high-speed data transmission.
Implementation Method 1
a power harvesting driver for obtaining an electrical power of a lower voltage, lower than the predetermined voltage, from at least one differential signal line coupled to the electronic device and powered by the electronic device
Implementation Method 2
a bootstrapping circuit for generating a startup voltage by obtaining power from at least one auxiliary control line coupled to the electronic device and supplying the obtained start-up voltage to the voltage raiser circuit provided the presence detector indicates the electrical power of the lower voltage is not available
Data Source
AI summary
A system for providing a power signal of a predetermined voltage to an input of a High Definition Multimedia Interface (HDMI) sink device is provided. The system includes an electronic device, generating HDMI signals transmitted on at least one differential signal line to another input of the HDMI sink device, and a startup circuit, providing the power signal of the predetermined voltage. The startup circuit includes a power harvesting circuit for obtaining an electrical power of a lower voltage, lower than the predetermined voltage, from at least one of the HDMI signals on the another input, and a voltage raiser circuit increasing the lower voltage to the predetermined voltage. A corresponding electronic cable containing the start-up circuit is also provided.