N-bit digitally tunable ultra wide-band pulse generator

Abstract

In this thesis, a new digitally tunable UWB pulse generator for an impulse type of pulse generator is developed. The pulse generator is realized with a low cost simple circuitry by using Step Recovery Diode (SRD), PIN diodes and microstrip transmission lines which are employed in the many basic UWB pulse generation circuits. During the pulse generation process, the generator initially generates sharp edges by using a Step Recovery Diode (SRD) from an applied low frequency input sinusoidal signal, and then the sharp edges are converted into short pulses with desired durations by utilizing parallel short-circuited stub with variable lengths. These variable length stubs are acquired by PIN Diodes and microstrip transmission line sub-sections. By adjusting the lengths of the microstrip transmission line, variable duration UWB pulses can be obtained. Also by controlling stub with the N sub-sections digitally, 2N variable duration UWB pulses can be obtained that is a significant improvement in UWB pulse generation. The digitally tunable UWB pulse generator has been designed, implemented during the studies by using microstrip line technology and yielded reasonable performance. Typical pulse durations varying from 550 to 1750 psec and from 900 to 2500 psec have been obtained experimentally for 2-bit and 4-bit pulse generator, respectively. Experimental results are also duplicated using simulations based on Agilent Advance Design System (ADS) platform.