An UWB GPR transient source based on avalanche transistor

Abstract

An Ultra-Wideband (UWB) transient source based on avalanche transistor is implemented in this paper. The trigger signal is produced by the first order avalanche transistor, and the inductance added in the output end of the trigger signal in parallel makes fall edge narrower, so that the width of the final pulse reduces from 2.9 ns to 1.14 ns while the amplitude maintains the same value. Two avalanche capacitances discharging on the load resistance in common are used to enhance the pulse amplitude. The experiment result achieves a periodic pulse with the width of 1.14 ns and the amplitude of -13.2 V, whose voltage utilization is up to 66% with 20 V supply voltage. Due to the circuit's low supply voltage and narrow enough pulse, and with the analysis of signal processing requirement, this UWB pulse generator is very appropriate to be integrated in portable superficial layer Ground Penetrating Radar (GPR).