What is test compression in DFT?
What is test compression in DFT?
Scan compression is the most commonly used design-for-test (DFT) architecture for reducing ATPG test application time and test data volume. A traditional compression structure is made up of three distinct blocks: a decompressor, a compressor, and an X-tolerance or X-mask.
What is test data compression?
Test compression is a technique used to reduce the time and cost of testing integrated circuits. The first ICs were tested with test vectors created by hand. Test compression takes advantage of the small number of significant values to reduce test data and test time.
What is scan compression?
Scan compression is a critical technology used in nearly every design, but it doesn’t come without costs. Nearly every design’s test methodology today implements this technology, which inserts compression logic in the scan path between the scan I/Os and the internal chains.
What is EDT in DFT?
Embedded deterministic test (EDT) is a manufacturing test paradigm that combines the compression advantage of built-in self-test with the high fault coverage of deter- ministic stimuli inherent to methods based on automatic test pattern generation and external testers.
Why test coverage reduces after scan compression?
Total test costs initially decline with compression due to the cost savings from tester cycle time reduction.
Which one is the first step in test compression?
Step One: The first step to configure compression test equipment is to gather background information on the types of metal samples you plan to test.
What is DFT architecture?
DFT architecture addresses and optimizes multiple design and manufacturing objectives (including timing, area and power) or today’s complex SoCs. • It offers a single environment for developing high-quality power-aware test architectures that do away with design iterations and eventually reduce cost.
What does compression level mean?
Compression levels, the amount of pressure applied to your extremities, are measured in millimeters of mercury (mmHg). The larger the number, the higher the compression. The different compression levels serve different purposes.
What is the difference between high compression and low compression engines?
A higher compression ratio (CR) is beneficial for engines. That’s because the higher ratio allows for an engine to extract more energy from the combustion process due to better thermal efficiency. Higher compression ratios allow the same combustion temperatures to be achieved with less fuel.
What is sequential depth in DFT?
sequential depth is the number of capture cycles executed before unloading your scan chains.
How is DFT compression ratio calculated?
If your uncompressed design has 10 scan chains with 10 scan channels, then the compression ratio is 1:1. If you add compression so the number of internal scan chains is 100, then the compression ratio is now 10:1 or 10x.
Why is scan compression performed in DFT nodes?
Hence, scan compression is performed for decreasing the pattern length and memory usage. After inserting the scan compression logic again, check and fix the DRCs and the number of the scan flop stitched in the single chain can decided by the compression ratio.
How is test compression used to reduce test time?
Test compression takes advantage of the small number of significant values to reduce test data and test time. In general, the idea is to modify the design to increase the number of internal scan chains, each of shorter length.
How is design for testability ( DFT ) based on ATPG?
It proved very difficult to get good coverage of potential faults, so Design for testability (DFT) based on scan and automatic test pattern generation (ATPG) were developed to explicitly test each gate and path in a design. These techniques were very successful at creating high-quality vectors for manufacturing test, with excellent test coverage.
Why do we need a DFT test infrastructure?
DFT architecture approach is very easy to deploy, and also accelerates the development of a higher-quality test infrastructure at a lower cost. The advanced built-in technology enables testability for analog and mixed signal designs with limited digital inputs.
