Study On The Nonlinear Transmission Lines For Pulse Compression

In modern society, development and progress of radar systems, wirelesscommunication systems has become a theme of world technological development.The increasing miniaturization and integration of microwave/RF circuits oncomponent and measuring instruments put forwards higher requirements. As themost important part of radar systems, communication systems and its measuringinstruments, the pulse width of the sampling circuit directly determines themaximum bandwidth and the overall performance of the entire system orequipment. With the continuous advancement of the technical level, the pulsewaveform width also continues to reduce, and it can already achieve picosecondand subpicosecond level, the ways of pulse generation are increasingly rich. Theways of using fast switching manner with tunnel diodes, step diode or avalanchediode to generate narrow pulses have their own devices limit, so the pulse widthis very difficult to reduce further. Proposal and development of the nonlineartransmission lines (NLTLs) brings a new direction to the reduction of pulsewidth.This dissertation discussed the NLTLs, first introduced the process of itsemergence and development, and deeply studied the composition, workingprinciple, the features and functions, and applications of that structure. Inparticular, the dissertation made a analysis of the three characteristics of thestructure which mainly affected the propagation characteristics of the NLTLs.Then the dissertation analyzed the important part-transmission lines in theory,modeled and simulated the so called slow-wave CPW, which was the improvedstructure of the coplanar waveguide. Finally, the dissertation designed combgenerator and pulse compression module with the function of pulse compressionof the NLTLs, and used the RF simulation software ADS to make circuitsimulation and parameter optimization, ultimately the comb generator with thepulse edge width less than40ps and pulse compression module more than60%was achieved. The realization of a picosecond or even subpicosecond pulse with analogcircuits is still difficult, and most of the pulse generating circuits are limited bythe diode cutoff frequency and its own characteristic curve. The emergence of theNLTLs brings new ideas for this research fields, and it can solve the difficultiesencountered currently.