Scan-based self-test structure and method using weighted scan-enable signals

Abstract

A scan-based self-test architecture and method using weighted scan enable signals is disclosed. The self-test architecture comprises: a linear feedback shift register; a phase shifter connected to outputs of the linear feedback shift register, and scan chains and the combinational part of the circuit under test; an AND gate; scan chains, each being formed by serially connecting multiple scan flip-flops having the same architecture; a multiplexer; and a logic unit for generating weighted random signal, whose inputs are connected with the phase shifter; the logic unit randomly selects the input pseudo random signals, weights the selected pseudo random signals, and assigns the weighted pseudo random signals assigned to the scan enable signals of the scan chains, to control the switching of the scan chains between the scan shift mode and the functional mode. The test effectiveness of scan-based BIST can be improved greatly using the test scheme with weighted scan enable signals.