A microcontrller conducted EMI model building for software-level effect

This paper proposes a model building process for conducted electromagnetic interference (cEMI) model of microcontroller (μC) considering software effect. Due to the fast advances of embedded system design technologies, software now is capable of controlling nearly all the features of electronic modules, which means software can actually affect EMI characteristics of target modules. Thus, a software-level EMI model is essential for electronic modules. Due to intellectual property (IP) considerations, IC designers seldom expose the internal architecture details of their IC products to EMI modelers. Because the internal module behaviors are unknown, it makes EMI modeling very difficult. This paper proposes a block-box cEMI modeling procedure for μC. The concept is based on a set of block-box impulse response (BBIR) functions. BBIR modeling method is based only on measurement information and treats the target as a block-box. After the model building process, the cEMI behavior of a new testing boards (or modules) with the same μC can be estimated. This model is verified by a case study. From the experiment results, it shows that the proposed method can estimate different machine code cEMI behaviors. The estimated result is in good accordance with the measurements both in time-domain and frequency-domain. The results also shows the internal impedances of a μC are quite different among machine codes executed by the μC.