Testing and inspection

In testing high-speed serial interfaces, which method loops the chip's transmitter output back to its receiver so the chip itself verifies communication?

  1. AIDDQ test
  2. BBurn-in
  3. CLoopback test
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Answer: C. Loopback test

Directly measuring high-speed SerDes reaching tens of Gb/s with a tester alone is difficult and expensive. A loopback test returns the transmitted signal to the receiver and checks for data errors with on-chip circuits. This lets general-purpose testers test high-speed interfaces efficiently.

  • A. An IDDQ test detects defects from quiescent supply current.
  • B. Burn-in is a stress test to remove early failures.
  • C. Correct. Transmission is looped back to reception for checking.
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More Testing and inspection questions

  1. What is the technique called that dynamically changes test items or limits per chip or per lot based on intermediate results and statistics, such as from wafer test?
  2. In AD converter testing, what is the main purpose of inputting a slowly varying sine wave or similar and counting how often each output code appears (a histogram)?
  3. For a chip that failed scan testing, what is the process called that logically narrows down candidate fault locations from which outputs mismatched on which patterns?
  4. Which technique models defects such as transistor shorts and opens inside standard cells based on each cell's circuit and generates test patterns for them?
  5. Which correctly describes wafer test (probe test)?