Space charge measurement system using high-frequency pulse generator

摘要

In pulsed electroacoustic method (PEA), averaging technique is necessary for the signal process to acquire waveform with higher S/N (signal to noise). It could be obtained by repeatedly applying the pulse voltage to the sample. The suitable minimum number of times for averaging depends on the measurement conditions and characteristics of equipment. For general measurement system, the number of times above 100 is necessary. This means the frequency of repeated pulse voltage should be higher enough to complete the data averaging in a short period. However, the frequency is low for conventional pulse generator used in general measurement system, leading to significant delay during data averaging. To overcome this disadvantage, a high-frequency pulse generator was design based on high voltage transistor switch in this paper. This pulse generator could output high voltage pulse with basis frequency up to 3 kHz and the pulse width in 5 to 10 nanoseconds. Moreover, a burst of 100 pulses can be issued on the basis frequency and the minimum pulse interval could be as low as 1 μs. Measurement with high-frequency pulse could reduce the time delay during data averaging effectively. Further more, a stimulation of the PEA system with extremely high-frequency pulses was accomplished indicating the huge influence of stray capacitance and inductance to the system.