A High-Performance Composite Electric Field Probe With Bandwidth 5 kHz–2 GHz of Normal and 5 kHz–500 MHz of Tangential

Progress of wide bandgap semiconductor devices has promoted the development of pulsed power switches to miniaturization, high power, and high repetitive frequency. The miniaturization and high power of switches mean that the chip and its surroundings face the challenge of high-voltage tolerance in a small space inevitably. Therefore, the potential insulation problem is particularly prominent. For insulation design, the quantitative characterization of the electric field strength at electrical weak points is fundamental. Current characterization methods mainly focus on simulation, but the accuracy and reliability of the results are constrained by the degree of modeling integrity and the inherent uncertainties of simulation. In addition, the existing measurement methods are generally not suitable for pulsed electric field. Therefore, for high-voltage pulsed conditions, based on the vector synthesis principle of electric field strength, two kinds of sensors suitable for measuring normal and tangential electric fields are designed in this article. Then, a composite electric field probe has been developed through board-level integration, capable of simultaneously detecting normal electric fields from 5 kHz to 2 GHz and tangential electric fields from 5 kHz to 500 MHz. The probe enables noncontact measurement inside switch modules for quantitative analysis of the pulsed electric field. The probe is tested with a grounded coplanar waveguide (GCPW) transmission line, and the near-field scanning of a series MOSFETs module is performed. Results show that the probe is capable of full bandwidth measurement for pulsed spatial electric field of switch modules, compared with existing probes of the same type, which is of great significance for insulation margin assessment and compact package design of modules. Finally, this probe is less expensive and offers excellent performance in terms of isotropy, suppression of unwanted field coupling, and spatial resolution.