A novel broadband capacitor voltage divider for measurement of ultrafast square high voltage pulse transmitted in transmission line

Bing Wei,Jinhui Liang,Weiping Xie,Hongwei Liu,Jianqiang Yuan

doi:10.1063/1.5109744

Abstract

This paper studies a new type of broadband capacitive voltage divider, which is used to measure the high voltage square wave pulse with sub-nanosecond front in a transmission line. The low-frequency characteristics of traditional capacitive dividers are extended by adding sampling resistors, and the high-frequency gain caused by stray capacitors of sampling resistors is eliminated by adding compensation capacitors, which greatly broadens the bandwidth of capacitive dividers. The findings show that when the sampling resistance is 6.1 kΩ and 12 kΩ and the equivalent grounding capacitance is about 15 pF and 30 pF, respectively, the bandwidth of the divider is 180 kHz to 2 GHz and 100 kHz to 2 GHz, which can meet the test requirements of the high voltage square wave pulse with sub-nanosecond front and dozens of nanosecond pulse width.

Highlights

The capacitance voltage divider is widely used in measuring high voltage pulses
The research on the capacitive voltage divider is usually based on the time domain characteristics, so the frequency domain characteristics of the capacitive voltage divider are not discussed
The ringing part representing the high frequency characteristics is substantially consistent with the waveform of the signal source, which is consistent with the frequency response test result

Summary

INTRODUCTION

The capacitance voltage divider is widely used in measuring high voltage pulses. It can work in differential mode (named D-dot) and self-integral mode. An additional matching integrator or software integration must be added to the test system This makes the test system more complicated. When measuring the square-wave voltage pulse at a subnanosecond front, the capacitive voltage divider is required to have a wide frequency response range. The traditional capacitive voltage divider has a low frequency lower limit, which makes the flattop drop when measuring a square-wave pulse with a certain pulse width. The stray capacitance of the sample resistor with a larger resistance value will cause high-frequency gain and exacerbate its high-frequency characteristics, making it impossible to measure sub-nanosecond front pulses.

PRINCIPLE OF OPERATION

DESIGN OF THE CAPACITOR VOLTAGE DIVIDER

TEST METHODS OF THE VOLTAGE DIVIDER

Findings

CONCLUSION