Test Decompressor Effectivity Improvement
Ondřej Novák, Jiří Jeníček, Martin Rozkovec · 2016
We propose a sequential test pattern decompressor enabling dynamic reseeding. It reduces dependency between the decompressor output bits during the first few clock cycles after decompressor reset. Due to this fact, a lower number of clock cycles is necessary to be performed in order to encode test patterns. We evaluated features influencing the decompression quality and the hardware overhead for different decompressor principles. According to the evaluation results, we propose a decompressor combining a combinational linear decompressor and an linear feedback shift register (LFSR) like automaton, we place the combinational decompressor on the LFSR inputs. We demonstrate that due to this arrangement the combined decompressor can be used without any phase shifter and/or state skipping ability of the LFSR. We have experimentally verified that adopting the proposed decompressor structure improves test coverage, saves the hardware resources and shortens the test application time.