An Ultra-wideband Adjustable Pulse Generator Design

Adjustable pulse generator can realize variable bandwidth TDR, variable transmission distance and variable resolution UWB, which has important application value. Our research team uses a variety of pulse generators in the development of Time Domain Reflectometers for high-speed communication networks and high-performance computer test. This article describes in detail the design process of a low-cost width adjustable pulse generator based on a planar microstrip structure. The fast recovery characteristics of the step recovery diode (SRD) are used to generate a step signal with a very short transition time, and then the short route is inverted and combined with the original signal to obtain a Gaussian broadband pulse. We used a simplified pulse shaping circuit, since the width of the pulse signal depends on the length of the short route, so the PIN diode is connected in parallel on the delay line to form a single pole single throw switch (SPST), changing the switching state to control the effective length of the microstrip transmission line, so that the pulse width is adjustable at 250-650ps. Measured results also confirm the simulations.