A low-cost microstrip UWB pulse generator with integral biphase switching modulation

We report on preliminary results from the development of a low-data rate, low-cost, Ultra-wideband (UWB) pulse generator which uses an RF Step Recovery Diode (SRD) on microstrip board. A circuit employing a single Skyworks CVB1031 SRD part on Rogers RT/Duroid 5870 RF board has been developed using HP Advanced Design System (ADS) software; initial simulation results show that sub nano-second (0.4 - 0.6 ns) monocycle wideband pulses with a repetition period of 2.5 ns (400 MHz) are achievable. While wideband pulse generators using SRD parts have been verified elsewhere [5, 7], the novelty in this work is that a six-finger, interdigitated Lange Coupler, employing an LC tank switching technique previously demonstrated at integrated circuit (IC) level [8], has been added to the pulse generator to yield a bi-phase pulse modulation technique. Pilot findings show a high degree of symmetry between the bi-phase output pulses, demonstrating how an RF pulse generator, designed with low-cost microstrip board and SMD techniques, has the potential to be used as a cost-effective pulse modulator solution in the physical layer of a wideband communication system.