Signal Generator ISI Control via Digital IIR Filter
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Solution Overview
Problem
Current methods for generating intersymbol interference (ISI) in high-speed serial data testing are limited by fixed trace lengths on circuit boards, lack of fine control over ISI values, and require time-consuming recalibration when changing trace lengths or associated jitters, leading to inconsistencies due to external components.
Innovation Solution
A signal generator device with a central processing unit and user interface that allows precise control over ISI parameters, using a single pole digital infinite impulse response (IIR) low pass filter to generate serial data patterns with adjustable ISI effects, enabling incremental calibration and accurate waveform generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If fixed trace lengths are used on circuit boards to generate ISI, then the device structure is simple, but the adaptability and fine control over ISI values are limited
Solution Approach 1:
The patent applies parameter changes by using a digital signal processor to dynamically adjust ISI parameters through software control. Instead of changing physical trace lengths, the system modifies digital parameters to generate different ISI effects, enabling fine control over ISI values from 0 to 1 UI in incremental steps while maintaining a simple hardware structure.
Solution Approach 2:
The patent replaces the mechanical/physical system of fixed circuit board traces with a digital signal processing system. The physical trace length adjustment is substituted by digital parameter modification in the signal generator, allowing ISI to be controlled through software rather than requiring physical reconfiguration of the circuit board.
2Ease of operation
If multiple trace lengths are used to achieve different ISI values, then the range of ISI control is improved, but the calibration time and system complexity increase
Solution Approach 1:
The patent implements self-service through automated calibration procedures. The signal generator automatically performs calibration when switching between different ISI settings, eliminating the need for manual calibration by operators. The system self-adjusts and self-verifies the ISI parameters, reducing both calibration time and operational complexity.
Solution Approach 2:
The patent applies dynamics by making the ISI generation system dynamically adjustable through software control. Instead of static fixed traces, the system can dynamically change ISI parameters in real-time, allowing rapid switching between different ISI values without requiring physical reconfiguration or extensive recalibration.
3Manufacturing precision
If external components like connectors and cables are used in the test system, then the system is easier to assemble, but the ISI generation accuracy deteriorates due to interference
Solution Approach 1:
The patent extracts and eliminates the source of interference by generating ISI effects directly in the digital domain before signal transmission. By creating ISI through digital signal processing rather than relying on external physical components to introduce interference, the system removes the need for calibrated external components and achieves more accurate and stable ISI generation.
Data Source
AI summary
A device and method for generation of Intersymbol interference (ISI) effects on serial data by direct digital synthesis is described. The features of the present invention allow a user to set parameters such as data rate, voltage amplitude, encoding scheme etc. as per requirements. An ISI parameter value is selected and applied to the serial data to produce ISI effects in the serial data. Alternatively according to another feature the patterns may be set as per industry standards.