On the development of a compact sub-nanosecond tunable monocycle pulse transmitter for UWB applications

Development of a new sub-nanosecond monocycle pulse transmitter with tunable pulse duration for short-range low-power ultra-wideband radar and communication systems is presented along with detailed design and analysis. The developed pulse transmitter is simple, compact, and can be realized using planar or uniplanar integrated circuits. A novel RC coupling circuit along with a high driving current, provided by a high-speed amplifier and buffers, are used to obtain an increase in the output power. A decoupling circuit is implemented to reduce ringing on the monocycle pulse and provide necessary pulse clamping. Tuning of the output monocycle-pulse duration is achieved by using two distributed delay lines, coupled together by the decoupling network, each spatially loaded with antiparallel p-i-n diodes that are alternately switched on and off. Measurement results show tunable monocycle pulse durations in range of 0.4-1.2 ns, approximately corresponding to the operating frequency range of 0.15-3.7 GHz, and 200-400 mW of pulse peak power. The calculated and measured pulse durations also agree reasonably well.