Design of RF Current and Voltage Probes for IC Conducted Emission Measurement

Improved RF current and voltage probes are developed for evaluating IC conducted emission (CE). Flatness of the insertion loss (IL) is a critical performance indicator for IC CE testing, as it directly affects measurement accuracy and repeatability. This work analyzes several key factors on the IL flatness of the probe, including component parasitic effects, PCB layout, and the resonance of the metallic shell. To mitigate resonance and enhance flatness, a design strategy employing small-package components, cross-layer parallel resistor networks, a coplanar waveguide (CPW) transition, and absorbing materials is implemented. Calibration results demonstrate that both probes comply with the requirements of IEC 61967-4 and have a substantially extended operational bandwidth. To further validate the performance of the proposed probe, a comparative experiment was conducted against a commercial probe. Finally, CE measurements were performed on a DC-DC buck converter, and the measurement uncertainties were evaluated.