Frequency response characteristics of self-integralting capacitive divider

A self-integrating capacitive divider has been designed to measure the high voltage pulse transmitting in a cable with rising time of 1ns. The frequency characteristics have been analysed by the equivalent circuit that comprises stray parameters of capacitive divider. The main factor affecting the lower limiting frequency is the time constant, i.e., the product of the capacitance of the low-voltage arm capacitor and the resistance of the equivalent load. The upper limiting frequency is chiefly impacted by some stray parameters which stem from the stray inductance of the low-voltage arm capacitor and the stray capacitance of the compensated resistor. To extend the lower limiting frequency the time constant should be increased by enhancing the capacitance or the resistance, however, this often results in the debasement of the upper limiting frequency. Different compensating resistors have been designed. The amplitude-frequency response of the capacitive dividers were measured by network analyzer, meanwhile, experiment with square pulse response was also performed as a contrast. The results indicate that the upper limit of frequency response for capacitive divider with 550 Ω compensating resistance exceeds 2 GHz, however the lower limit is insufficient and about 1.8 MHz. If the compensating resistor is tuned to 6.6 kΩ, the corresponding capacitive divider will have a bandwidth of 0.17-700 MHz which satisfies the demand of measurement.