Crosstalk fault testing by the built‐in self‐test method with test points and phase shifters

Abstract

SUMMARYWith the progressive decreases in size and increases in the speed of VLSI, guaranteeing signal integrity has become important. This paper focuses on crosstalk as a factor responsible for the violation of signal integrity and proposes a method of testing for crosstalk faults. The builtin self-test (BIST) method, which can detect crosstalk faults by using an M-sequence of a linear feedback shift register (LFSR), has been proposed. But since the output of the LFSR is used unaltered as a random test pattern, an insufficient number of crosstalk pulses is excited and some faults escape detection. We therefore propose the use of a new testing circuit which increases the number of crosstalk pulses that are excited and makes possible the detection of faults that were previously undetectable. The new testing circuit uses test points and phase shifter circuits which can output sequences that have arbitrary delays from the M-sequence. In addition, by changing the simulation method, it also becomes applicable to large-scale circuits for which such simulations could not be used in the past. We evaluate the detection rate and area overhead for several benchmark circuits and show that the method is effective in detecting crosstalk faults.