Design of a Novel V-Dot Coaxial Pulse Probe With Wideband 0.01–1 GHz

The measurement of square wave signals with sub-nanosecond (<1 ns) front challenges in terms of achieving a high cut-off frequency, a high attenuation ratio, and wideband characteristics. In this article, we propose a high-resistance matching circuit for pulse measurement. Additionally, we develop a prototype self-integrating capacitive voltage divider probe (V-dot) utilizing a coaxial divider structure. On the one hand, the prototype employs the coaxial transmission line as the fundamental structure of the probe to effectively constrain the parasitic parameter of the probe. On the other hand, the oscilloscope’s high-resistance load of 1 M<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $ </tex-math></inline-formula> effectively enhances the low-frequency performance of the probe. The “ringing” phenomenon of the loop under high-resistance load is further analyzed in this study. To achieve wideband measurement, waveform distortion is effectively suppressed by incorporating a damping resistor and limiting the length of the transmission signal line. Finally, by conducting electromagnetic field simulation, network analyzer inspections, and calibrating experimental standard signal generators, we demonstrated that the proposed coaxial pulse probe has a wideband range of 10 MHz–1 GHz, a leading-edge response time of approximately 350 ps, and a measurement error of less than 3%.