IEEE 1149.4 Mixed Signal Test Standard
The IEEE 1149.4 mixed signal test standard is currently being developed as an extension of the 1149.1 digital-only standard. "Dot4" adds two new pins to the standard four, a FORCE pin and a SENSE pin, allowing Kelvin probing of external component networks to determine component values.
The P1149.4 standard will also define new techniques for driving "pseudo-dot1" signals on interchip analog lines, allowing board tests for analog lines to operate quite similarly to current 1149.1 digital "open and short" tests.
Analog testing is not nearly as simple as digital testing; this standard is a difficult one to develop. Issues such as performance degradation, the effects of ESD protection structures on metrology, and even the description of analog pins in a way suitable for automation are all thorny issues.
KLIC has developed optional extensions to the emerging 1149.4 standard, which will allow test engineers to perform accurate timing and voltage measurements, and extract high speed oscilloscope-like waveforms, using the low-speed dot4 interface. These are described in a paper given at the 1996 International Test Conference, Early Capture for Boundary Scan Timing Measurements , pages 417-422.
KLIC works with the 1149.4 committee, and designed a test chip to test the new 1149.4 standard against real world constraints.
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