MATLAB-Simulink based Framework for Combinational ATPG Applied to Testing of Digital Blocks in Analog and Mixed-Signal Circuits

Testing digital blocks embedded in analog and mixed signal (AMS) circuits poses several challenges to the test engineers. Addressing the challenges, the paper proposes a MATLAB-Simulink based framework for test generation as well as test application to combinational blocks embedded in AMS circuits without adding any design for testability (DFT) or additional circuits. In this framework, a well-known automatic test pattern generation (ATPG) algorithm is implemented in MATLAB-Simulink considering single stuck-at faults in the combinational circuits followed by fault simulation of the generated test patterns. While synthesizing the mixed-signal test stimulus which is to be applied to the inputs of linear analog block driving the digital block, the proposed approach exploits ‘analog backtrace’ method which is realized with the help of Simulink libraries. The test frequency is selected through sensitivity analysis to ensure that component variations in analog circuit have the least possible impact on the test generation and fault coverage. The effectiveness of the proposed method has been successfully verified through PSPICE simulation of AMS circuit structures formed by combinations of two benchmark analog circuits driving a benchmark combinational circuit. The simulation results show that the proposed framework can find a test sinusoid which can detect almost all single stuck-at faults in a combinational block resulting in fault coverage of nearly 100%.