TDR-Based Impedance Correction for High-Speed Interface Matching
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Solution Overview
Problem
Conventional impedance correction methods for high-speed transmission interfaces are costly and inefficient, as they require external precision resistors and do not account for the influence of circuit board impedance, leading to noise and reflection issues.
Innovation Solution
An impedance correction device and method that uses a step signal generator, detection unit, impedance calculation unit, and impedance setting unit to calculate and adjust the impedance value of a correction impedance within an integrated circuit, applying the principle of Time Domain Reflectometry (TDR) to match the characteristic impedance of the circuit board, thereby eliminating the need for external resistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If external precision resistors are used for impedance correction, then impedance matching can be achieved, but production costs increase
Solution Approach 1:
The patent extracts the impedance correction function from external precision resistors and relocates it inside the integrated circuit through the correction impedance unit. This eliminates the need for external precision resistors while maintaining impedance matching precision, thereby reducing production costs.
Solution Approach 2:
The integrated circuit performs self-diagnosis and self-correction of impedance mismatches through the detection unit and correction impedance unit. The system automatically detects impedance issues and adjusts internal correction impedance values without requiring external components or manual intervention, reducing both cost and complexity.
2Manufacturing precision
If conventional impedance correction methods are used, then impedance matching can be achieved, but the influence of circuit board impedance cannot be handled
Solution Approach 1:
The detection unit continuously monitors the actual impedance of the circuit board and feeds this information back to the correction impedance unit. This feedback mechanism enables the system to dynamically adjust the correction impedance to compensate for circuit board variations, achieving accurate impedance matching despite board impedance influences.
Solution Approach 2:
The system changes the impedance parameter of the correction impedance unit based on detected circuit board characteristics. By dynamically adjusting the correction impedance value, the system adapts to different circuit board impedance conditions and maintains optimal impedance matching.
3Manufacturing precision
If external precision resistors are used for impedance correction, then impedance matching can be achieved, but device complexity increases
Solution Approach 1:
The patent merges the impedance correction function with the integrated circuit by integrating the correction impedance unit and detection unit inside the chip. This consolidation eliminates external precision resistors and reduces overall device complexity while maintaining impedance matching precision.
4Reliability
If automatic impedance correction is implemented, then signal integrity can be improved, but production time increases
Solution Approach 1:
The impedance correction is performed automatically during the manufacturing process before final product assembly. The detection unit measures impedance characteristics and the correction impedance unit adjusts parameters in advance, ensuring signal integrity is established prior to shipment without requiring additional post-production adjustments.
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
This solution reduces production and testing costs by enabling automatic impedance correction within the integrated circuit, ensuring stable signal integrity and matching impedance values without external adjustments, thus addressing the limitations of conventional methods.
Implementation Method 1
applying the principle of Time Domain Reflectometry (TDR) to match the characteristic impedance of the circuit board
Data Source
AI summary
An impedance correction device and a method thereof are provided. A step generator is used to generate a step signal and send to a circuit under test. A reflected signal returned back from the circuit under test is used as a measurement signal; and the measurement signal can be measured to obtain a characteristic impedance value. When the measurement signal is greater than the initially measured step signal, an impedance value of a correction resistor is increased; when the measurement signal is smaller than the initially measured step signal, the impedance value of the correction resistor is reduced. Through adjustment of the correction impedance value, impedance matching between the correction impedance value and the characteristic impedance value is achieved.