PCIe Self-Test System Using FFC Differential Signal Loopback
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Solution Overview
Problem
Conventional PCIe testing methods require multiple functional test cards for different functions, leading to inconvenience due to the need for full data transmission testing, which is unnecessary for ensuring production quality and only requires electrical characteristic testing.
Innovation Solution
A self-test system and method using a first and second circuit interconnect card with CEM and FFC interfaces, connected to a board under test, where the central processing unit generates and provides differential signals to the cards through FFC interfaces to perform self-checks on the CEM slots, eliminating the need for full data transmission testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional full data transmission test is performed for PCIe, then comprehensive function detection is achieved, but test complexity and number of test cards required increases significantly
Solution Approach 1:
The patent extracts only the essential electrical characteristic testing requirements from the complete PCIe data transmission test. By focusing solely on connectivity and high-frequency signal characteristics rather than full data transmission functionality, the test system complexity is reduced while still ensuring production quality. This is achieved by using circuit interconnect cards with FFC interfaces that directly test electrical properties without requiring complete functional data transmission paths.
Solution Approach 2:
The patent uses circuit interconnect cards that create electrical signal paths between CEM slots without requiring actual PCIe data transmission functionality. The FFC (Flexible Flat Cable) interfaces establish direct electrical connections that replicate the essential signal transmission paths needed for electrical characteristic testing, eliminating the need for multiple specialized functional test cards while maintaining test effectiveness for production quality assurance.
2Reliability
If multiple functional test cards are inserted for different PCIe functions, then all PCIe functions are detected, but test operation convenience deteriorates
Solution Approach 1:
The patent employs circuit interconnect cards with FFC interfaces that serve multiple testing purposes simultaneously. A single card type can test different CEM slots and different electrical characteristics through the same interface mechanism, eliminating the need to insert different specialized functional test cards for different PCIe functions. This universal approach maintains comprehensive detection capability while significantly improving operational convenience.
3Reliability
If full data transmission test is performed, then complete PCIe functionality is verified, but test efficiency decreases due to unnecessary testing
Solution Approach 1:
The patent applies partial action by performing only the necessary electrical characteristic testing (connectivity and high-frequency signal characteristics) rather than complete data transmission testing. For production quality assurance, this partial testing approach is sufficient and eliminates unnecessary testing steps, thereby improving test efficiency while maintaining adequate quality verification. The FFC interface-based testing provides the essential electrical validation without the overhead of full functional data transmission tests.
Data Source
AI summary
A self-test system for PCIe and a method thereof are disclosed. In the system, a first circuit interconnect card and a second circuit interconnect card are inserted into CEM slots, respectively, and the first circuit interconnect card and the second circuit interconnect card are electrically connected to each other through a FFC, the central processing unit generates and provides differential signals to the first circuit interconnect card and the second circuit interconnect card; the first circuit interconnect card or the second circuit interconnect card provide differential signals to the second circuit interconnect card or the first circuit interconnect card through the first FFC interface and the second FFC interface, respectively, and the second circuit interconnect card or the first circuit interconnect card provides the differential signals to a central processing unit, so as to implement self-check for PCIe.