High-Speed Serial Transmitter Test Receiver Using Beat Frequency Analysis
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Solution Overview
Problem
High-speed serial transmitters are difficult to test during production due to the need for expensive lab equipment or equipment upgrades, often resulting in untested transmitters that may prematurely fail or not meet specifications.
Innovation Solution
A testing device comprising an input stage with latched comparators, a digital-to-analog converter, and an analysis unit that includes a data processing unit and state machine, capable of analyzing differential output signals to measure jitter, differential swing, and transition time, using a beat concept with a clock signal shift to extract these characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If expensive lab equipment or equipment upgrades are used for testing high-speed serial transmitters, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent creates a simplified test receiver that replicates only the essential functions needed for production testing. Instead of using complex lab equipment, the invention implements a test receiver with latched comparators and basic signal processing capabilities that can measure critical parameters like jitter and signal quality without requiring full-featured expensive test equipment.
Solution Approach 2:
The test receiver is designed as a cost-effective, simplified device suitable for production testing environments. It uses basic components like latched comparators and simple signal processing circuits rather than expensive laboratory-grade equipment, making it economically viable for high-volume production testing.
2Measurement precision
If expensive lab equipment is used for testing, then measurement precision is improved, but ease of manufacture deteriorates
Solution Approach 1:
The test receiver is designed to be self-contained and autonomous, performing measurements without requiring complex external laboratory equipment. The device includes its own signal processing, comparison logic, and measurement capabilities, making it independent and easy to integrate into production test lines without requiring specialized lab environments or expertise.
3Ease of manufacture
If production testing is implemented with simplified equipment, then ease of manufacture is improved, but measurement precision deteriorates
Solution Approach 1:
The patent extracts only the essential measurement functions needed for production testing from complex laboratory equipment. The test receiver implements specific critical measurements such as jitter detection, signal level comparison, and quality assessment using simplified circuits like latched comparators, while omitting unnecessary complex features of full laboratory test systems.
Solution Approach 2:
The test receiver acts as an intermediary device between the transmitter under test and the production test system. It provides a bridge that translates high-speed serial signals into measurable parameters using intermediate processing stages like latched comparators and clock recovery circuits, enabling accurate measurements without requiring direct connection to expensive laboratory equipment.
Data Source
AI summary
A testing device for testing a high-speed serial transmitter or other device includes an input stage having a first comparator, a second comparator, and a digital-to-analog converter. The first comparator compares first differential signals from a device under test. The second comparator compares the first differential signals and second differential signals from the digital-to-analog converter. An analysis unit identifies first beats based on an output of the first comparator and second beats based on an output of the second comparator. The analysis unit identifies one or more characteristics of the device under test (such as jitter, differential signal swing, and transition time) based on the first and second beats. A clock unit provides an adjustable clock signal to the comparators. The clock signal may have a frequency shift with respect to a frequency of the device under test.