An algorithmic approach to optimizing fault coverage for BIST logic synthesis

Most approaches to the synthesis of built-in self test (BIST) circuitry use a manual choose-and-evaluate approach, where a particular BIST generator is chosen and then evaluated by faultsimulating the design with the vectors that the chosen generator generates. We develop an algorithmic synthesis-during-test approach in this paper, wherein the tasks of synthesizing the BIST logic and directed test pattern generation (DTPG) are intertwined to maximize the resulting fault coverage. Our approach is applicable to a variety of BIST strategies including those that use linearand nonlinear-feedback shift registers. We show how our method can be used to synthesize LFSR polynomials, LFSR seeds, LFSR weights, nonlinear feedback, or bit-fixing logic. Experimental data is presented.