Programmable HDMI Cable PCB Boost Circuit for 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 effectively address due to power constraints and variability in cable characteristics.
Innovation Solution
A programmable cable with an embedded boost device that uses a voltage boost circuit and power converter to obtain power from the differential signals, incorporating a deskew circuit and equalizer to compensate for signal skew and bandwidth limitations, and a calibration method to optimize performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If passive equalizer circuits are embedded in the cable, then signal quality is improved, but the solution is limited by power constraints and cannot adapt to varying cable characteristics
Solution Approach 1:
The patent applies dynamics by transitioning from fixed passive equalizer circuits to programmable active equalizer circuits that can dynamically adjust their parameters. The equalizer circuits include programmable gain amplifiers and filters whose characteristics can be modified via control signals, allowing adaptation to different cable lengths and conditions while maintaining signal quality.
Solution Approach 2:
The patent implements parameter changes by making the equalizer circuit parameters programmable and adjustable. The equalizer circuits can change their gain, bandwidth, and other parameters based on detected cable characteristics, enabling the system to optimize performance for varying cable conditions rather than being fixed to a single set of parameters.
2Reliability
If active boost devices are embedded in the cable, then signal quality and adaptability are improved, but power consumption increases and external power sources are required
Solution Approach 1:
The patent applies self-service by enabling the embedded boost and equalizer devices to power themselves using the differential data signals passing through the cable. The power management circuit harvests energy from the signal current, eliminating the need for external power sources while maintaining the active processing functions for signal enhancement.
Solution Approach 2:
The patent uses the differential data signals as an intermediary to provide power to the boost and equalizer circuits. The signal current that carries data also serves as the power source, with the power management circuit extracting and regulating this energy to supply the active components.
3Length of moving object
If cable length increases, then transmission distance is improved, but bandwidth decreases and signal distortion increases
Solution Approach 1:
The patent applies parameter changes by using programmable equalizer circuits that can adjust their frequency response and gain characteristics based on the detected cable length. The equalizer parameters are modified to compensate for the increased attenuation and bandwidth loss in longer cables, effectively restoring the signal quality despite the length increase.
Solution Approach 2:
The patent implements feedback by incorporating cable characterization that detects actual cable properties including length, and uses this information to automatically adjust the equalizer and boost circuit parameters. This closed-loop approach allows the system to optimize performance for the specific cable installation, compensating for length-related degradation.
4Reliability
If differential skew compensation is implemented, then signal integrity is improved, but device complexity increases
Solution Approach 1:
The patent applies merging by combining the differential skew compensation function with the equalizer and boost circuits into a single integrated programmable signal processing unit. Rather than adding separate dedicated skew compensation hardware, the patent implements skew correction through the programmable parameters of the existing equalizer circuits, reducing overall complexity.
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 significantly improves signal quality by compensating for differential skew and bandwidth limitations, enhancing the reliability and performance of high-speed data transmission in HDMI cables without requiring external power sources.
Implementation Method 1
A programmable cable with an embedded boost device that uses a voltage boost circuit
Implementation Method 2
power converter to obtain power from the differential signals
Data Source
AI summary
An HDMI cable carries high speed encoded data which are transmitted differentially over data channels, along with a clock. High-frequency loss and differential skew within a differential signal may be compensated by analog circuits embedded in the cable. These embedded circuits are tuned at production for best performance by observing the quality of the recovered analog signal. The embedded circuits are powered by a combination of power sources, both carried within the cable, and harvested from the high-speed signals themselves.