A Path Selection Flow for Functional Path Ring Oscillators using Physical Design Data

A lot of effort and money is invested in testing to ensure zero-defect quality of automotive microcontrollers. One crucial test is the performance screening. Indirect structures such as Ring Oscillators (ROs) are used for this. Here, the quality of the performance screening strongly depends on the quality and selection of the RO structures used. This paper proposes a path selection and implementation method to provide a set of functional path ROs with good representativeness for the whole chip. In addition, a simulation-based validation is presented, which is used to improve the selection process continually. The proposed path selection is validated by simulation and on silicon. The results show a high diversity and good coverage of the chip parameters with the selected functional path ROs, providing good conditions for a high-quality performance screening.