Frequency compensation for resistive voltage divider using specially shaped inner conductor

The main factor that slows down the high-frequency response of a resistive voltage divider (RVD) is the distributed stray capacitance (C_g) between the high-voltage-arm (HVA) and the grounded conductors, due to the charging and discharging of C_g through the high resistance R_H of the HVA with characteristic time R_HC_g. Based on a RVD consisted of ceramic tube resistors, a compensation method utilizing the distributed capacitance between a specially shaped inner conductor and the HVA was proposed in this paper, which is more compact than grading rings and can work well with grounded shielding. The method was verified by electromagnetic simulation, which indicated a bandwidth improvement from 3 MHz to more than 1 GHz for the prototype RVD with grounded shielding. Experimental results showed that the 10%-90% rise time for a step input was improved by the compensating electrode from ∼90 ns to 1.25 ns. The main drawback of the method is the possible degradation of insulation when precise compensation is required.