Power Optimized Dictionary Coding for Test Data Compression

To handle large volume of test data required for testing a System-on-a-Chip (SoC) demands test data compression techniques. Again power consumption during testing is becoming a major concern. Our paper presents a method of reducing power taking into consideration the dictionary based compression technique proposed in literature, where indices of the dictionary are used for compressing test data. Paper shows how power can be reduced by judicious allocation of dictionary indices to the coded words and the prefix bit selection to differentiate dictionary and non-dictionary entries. The power reduction achieved does affect neither the compression ratio nor the Test Application Time (TAT). It also does not increase the hardware overhead. Experimentation with ISCAS89 benchmark circuits shows up to 71% saving in power.