A Miniature High-Sensitivity Active Electric Field Probe for Near-Field Measurement

A noncontact active electric field probe with miniature size and high sensitivity is designed for the noise location in electronic systems from 9 kHz to 1 GHz. This probe is fabricated in a multilayer printed circuit board (PCB) (dielectric constant of 4.2 and loss tangent of 0.02). The minimum width of the probe is 4 mm, and the length is 48 mm, which allows it to be used in compact and complex space like the PCB and the integrated circuit. The dual-stage amplifier circuit and the door-shaped structure are applied to the probe design, which improves the transfer gain of the probe 40-50 dB higher than that of an equivalently sized passive electric field probe. The spatial resolution is 0.6 mm, while the height of the probe tip above the device under the test is 0.3 mm. The proposed probe is verified with three-dimensional electromagnetic simulation and near-field measurement.