Model and simulation of a new ultra-narrow trigger frequency alterable pulse generator

Abstract

Two new kinds of ultra-narrow trigger frequency alterable picosecond pulse generator are presented. One can produce positive pulses and the other can produce negative pulses. The two pulse generators are subdivided into three parts: signal driving circuit, differentiator network and pulse shaping circuit. The pulse shaping circuit is made of step recovery diode (SRD) and short-circuit microstrip line. A positive pulse with width of 54 ps (50%-50%), rising time of 30 ps (10%-90%) and falling time of 32 ps (90%-10%), and a negative pulse with width of 54 ps (50%-50%), rising time of 30 ps (90%-10%) and falling time of 30 ps (10%-90%) are achieved in simulation. All of the components are ready-made and inexpensive. They can be applied in ultra-wideband (UWB) communication system, such as transmitters and receivers. Key words: pulse generator, ultra-narrow, step recovery diode (SRD), pulse shaping circuit CLC number: TN 92 Document code: A IntroductionUltra-wideband (UWB) technology has many attractive characteristics, such as low power, strong penetrating ability, high accuracy of positioning and high data rates, and thus can be a good candidate in the application of radar and communication systems. For example, UWB technology can be used in ground or wall penetrating radar [1] , radar sensor [2] , radar imaging [3] , and precision locating and tracking. Under the authorization of Federal Communications Commission (FCC), UWB can develop communication systems, especially those requiring short range and high data rates. A pulse generator is a key component in the UWB subsystems, such as receivers and transmitters. Moreover, a pulse generator whose input frequency is alterable to a certain degree, and whose duration is extremely short is desirable in practical use.Conventionally, there are several ways to design a pulse generator, such as logic circuit [4] , nonlinear transmission line (NLTL) [5] , photonic domain techniques [6] ,