Design And Development Of Sub-Nanosecond Pulse Source With High Repetition Frequency And High Peak Power

With the deepening of UWB pulse signal research and the continuous optimization of peak power,trigger jitter,repetition frequency and other indicators,UWB pulse signal source is widely used in various military and civilian fields,such as UWB communication,radar detection,bioelectromagnetism,and food processing.There are a variety of pulse signal generation methods.Among them,the Marx circuit uses a low-voltage DC power supply to charge capacitors in parallel,and then discharges in series to generate a high-voltage pulse,which is favored by many researchers.To improve the working ability of the UWB pulse signal,higher pulse amplitude has become the focus of research,which directly determines the peak power and propagation distance of the pulse signal.Faster pulse repetition frequency determines the efficiency of the signal.At the same time,in order to obtain a wider signal spectrum,the rising edge of the pulse signal needs to be faster and the pulse width needs to be further narrowed.In addition,the low-time jitter of the pulse signal and the stability of the pulse signal source are also important standards.These requirements put forward high standards for the current UWB pulse signal source in all aspects.Through this study,the traditional avalanche transistor Marx circuit is improved,and an ultra-wideband pulse signal source with high repetition frequency and high peak power is designed and developed.On this basis,it is further improved to make the working stability of the signal source higher.The main contents of this thesis are as follows:By comparing different pulse signal generation circuits,the Marx circuit form based on avalanche transistors is determined.After parameter calculation,the circuit series,charging capacitance,current-limiting resistance,and other component parameters are determined.Through simulation and experimental testing,the scheme of increasing the number of avalanche transistors in parallel is determined,so as to reduce the load of avalanche current on a single transistor,reduce the stray inductance of pins,and greatly improve the working life and stability of the circuit.Through the experimental test,the gradually increasing capacitance value and gradually decreasing resistance value are finally selected to ensure that the power in each cycle is sufficient and the output amplitude and pulse width meet the required indicators.The trigger signal generation circuit is designed to output an output signal with the high amplitude and fast leading edge.This signal is used to trigger the avalanche transistor to reduce the pulse jitter.The pulse source is cooled by using heat dissipation equipment such as copper plate,fin,and air cooling so that the pulse source can work under the condition of high repetition frequency,achieve the balance of heat generation and heat dissipation,and output a more stable pulse signal.Finally,a time-domain UWB pulse signal source is developed,which can output pulse signals with the pulse width of 792 ps,leading edge of 182 ps,pulse amplitude of4.6KV and repetition rate of 100 k Hz.