Internal Cable Signal Impairment Calibration and Compensation
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Solution Overview
Problem
High-speed data communication devices, such as those using USB 3.0, face signal integrity issues due to signal impairments introduced by internal cables, which are not well-defined in existing standards, leading to potential failures even after passing compliance tests when connected to external devices.
Innovation Solution
A method and apparatus for calibrating and compensating signal impairments in internal cables by measuring intra-pair skew and frequency-dependent insertion loss during a calibration phase, using a loop-back signal to determine transmit and receive impairment settings, and applying these settings to adjust signals for compensation during normal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If internal cables are used in high-speed data communication devices, then device functionality and connectivity are improved, but signal impairments such as intra-pair skew and insertion loss increase, degrading signal integrity
Solution Approach 1:
The patent applies preliminary action by performing calibration measurements during a calibration phase before normal data communication occurs. The system measures signal impairments (intra-pair skew, insertion loss) using loop-back signals and stores these impairment values for later compensation during actual data transmission, thereby proactively addressing signal integrity issues before they affect communication reliability
Solution Approach 2:
The patent implements feedback by using loop-back calibration signals to measure the actual signal impairments introduced by internal cables. The measured impairment values are fed back to the compensation module, which then adjusts transmit and receive signal characteristics to compensate for the measured impairments, creating a closed-loop system that adapts to actual cable performance
2Productivity
If data communication data rate is increased, then transmission speed and productivity are improved, but signal impairments become more severe and signal integrity becomes more difficult to maintain
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting signal transmission parameters based on measured impairments. The compensation module modifies transmit signal characteristics (amplitude, timing) and receive signal processing parameters to counteract frequency-dependent insertion loss and intra-pair skew, enabling high-speed data transmission while maintaining signal integrity through adaptive parameter adjustment
3Reliability
If calibration measurements are performed to characterize cable impairments, then signal integrity is improved through compensation, but calibration time and system complexity increase
Solution Approach 1:
The patent applies self-service by enabling the system to perform its own calibration using built-in loop-back calibration signals and measurement capabilities. The calibration process uses the device's own transmit and receive paths to measure impairments, eliminating the need for external calibration equipment and reducing system complexity while maintaining measurement accuracy
Solution Approach 2:
The patent uses copying by creating virtual copies of the calibration signal path through loop-back connections. Instead of physically measuring the cable with external equipment, the system sends calibration signals through the cable and measures the returned signals, creating a virtual measurement copy that simplifies the calibration process while maintaining accuracy
Data Source
AI summary
Systems and methods are provided to calibrate and compensate for signal impairments from the use of cables in data communication devices. Signal impairments such as intra-pair skew of differential signals and frequency dependent insertion loss are measured during a calibration phase. One end of the cable is connected to a communication device. The other end of the cable is configured to loop back calibration signals transmitted from the communication device. The calibration signals looped back from the communication device are received and measured by the communication device. The measured impairments are used to determine transmit and receive impairment compensation settings to compensate for impairments caused by the cable. These settings are stored and used to adjust signals transmitted from the communication device to compensate for the transmit impairment. These setting are also used to adjust signals received by the communication device to compensate for the receive impairment.