METHOD OF DIAGNOSING SELF-DIAGNOSIS LOGIC INTEGRATED CIRCUIT AND SELF-DIAGNOSIS LOGIC INTEGRATED CIRCUIT

摘要

PROBLEM TO BE SOLVED: To eliminate, with less number of additional circuits, an excessive random number change rate causing a problem in a self-diagnostic LSI where a linear feedback shift resistor(LFSR) is used in a random number generating circuit (RPG). SOLUTION: Two differential types of random number pattern generators RPG1-110 and RPG2-120 operating with a system clock and a random change rate reduction circuit 130 are provided. The RPG1-110 is used for generating random numbers and RPG2-120 is used for reducing and controlling the change rate. When an output from the RPG2-120 is zero, an output from the RPG1-110 is kept unchanged, and the change rate of the random number output from the change rate reduction circuit 130 is reduced. As a result, the averaged value of continuous lengths of one or zero of random numbers for shift-scanning a group of flip-flops inside an inspected circuit 150.