Design for testability of combinational circuits

Abstract

A new concept of design for testability is being proposed, based on the properties of signals, gates and logical structures. This allows obtaining of reconfigurable elementary digital structures (REDS), which can work both in normal mode and in testing/ diagnosis mode. In the same way as on a filed covered with snow any non-uniform object can be observed, the digital structures, designed on REDS base, allow the control of all defects ≡0, ≡1, using of only two stimulating-vectors. Diagnosis of singular constant defects ≡0, ≡1 of combinational circuits (CC) requires about 2*n stimulating vectors, where n represents the number of primary inputs of the circuit. The cost of these facilities is doubling the number of active components on a chip and including of 2 pins in order to guarantee the reconfiguration of the verified structure. In case of a CC generalized model - including of 2 more pins in order to “homogenate” an arbitrary CC with different parities of the convergent signals.