An Efficient Capacitance Extraction Method for Multichip Power Modules for EMI Analysis

Extracting parasitic capacitances in multi-chip power modules (MCPMs) is essential for reliable electromagnetic interference (EMI) analysis, especially in in switching systems such as automotive inverters or converters. Such applications increasingly employ multi-bridge MCPMs—where multiple halfbridge cells are integrated and each bridge drives a different motor or load— making the characterization of capacitance more critical. Conventional approaches, such as curve tracers and transient fitting techniques, suffer from limitations including single-frequency measurement, a complex measurement setup, and the need for repeated tests under different bias conditions. These drawbacks limit their practicality for complex modulelevel characterization. This paper proposes a generalized capacitance extraction method based on two-port S-parameter measurements. The proposed method enables modeling of both static and dynamic capacitances under various voltage biases, with minimal reconfiguration of terminal connections. Experimental validation using a commercial IGBT-based MCPM demonstrated that the proposed method significantly reduces setup complexity compared to conventional measurements. These results confirm that the method is effective for EMI analysis and modeling of advanced MCPMs.