Novel On-State Voltage Measurement Circuit Topology, Operation, and Performance for High-Voltage Wide-Bandgap Devices

Accurate measurement of ON-resistance of semiconductor devices serves as a key indicator of how various stress factors impact the electrical, thermal, and long-term reliability performance of wide bandgap devices. Monitoring ON-resistance not only offers technical insight into device physics and degradation mechanisms, but is also used as a diagnostic precursor to device failure and aging. This is particularly important for high-voltage, fast-switching devices, such as wide bandgap (WBG) semiconductors, where precise in-situ measurement of ON-resistance during operation is necessary to assess the device's state of health. Such measurements involve monitoring the device current and ON-state voltage with high accuracy and resolution, while ensuring minimal delay and high-voltage blocking capability. Moreover, these measurements should be immune to variations in device temperature and load conditions as much as possible. In this paper, a novel measurement topology based on a cascode current mirror configuration is introduced and analyzed in depth. A detailed analysis of the circuit's operating principles, including both large-signal and small-signal behaviors, is provided, and the measurement performance is validated through hardware experiments under varying voltage and current conditions. The proposed approach integrates the strengths of existing measurement techniques while addressing the limitations identified in the literature. The experimental results of the proposed circuit presented in this paper demonstrate that the circuit exhibits high-resolution measurement with minimal voltage overshoot and undershoot, rapid dynamic characteristics, and accuracy across a wide range of operating conditions, making it highly suitable for high-voltage WBG semiconductor applications.