Study of nonlinear transmission lines and their applications

With the increasing market demand for wideband multifunctional electronic systems, real-time broadband measurement systems with few picoseconds switching rates are essential. Furthermore, stable millimeter wave sources are required to drive these wideband electronic systems. Nonlinear transmission lines (NLTLs) are high impedance transmission lines periodically loaded with reverse biased diode serving as varactors. Extremely high bandwidths are achievable because of the possibility to fabricate these structures monolithically, which is why pulses with ultra short transitions can be generated using NLTLs. Also, efficient wideband frequency conversion is made possible by NLTL technology.In this thesis, a comprehensive study of NLTLs and their applications is presented. Sharpening of the edges of electrical pulses, voltage dependent true time delay, and harmonic generation in NLTLs are investigated through analytical studies as well as circuit simulations and experimental measurements. Designing the best possible mixers, frequency doublers, and edge sharpeners and optimizing them are not the objects of this thesis. The main objective is to study an alternative design approach by using NLTLs. To this end, analytical solution for the magnitude of the third harmonic along a nonlinear transmission line is derived for the first time. Also, for the first time the lowpass nature of the NLTL is combined with the solutions for the magnitudes of harmonics in order to improve the validity range of the predicted harmonics. An NLTL harmonic generator is fabricated and measurement results are reported.Inspired by the distributed nature of nonlinear transmission lines, a novel filtering method is introduced for the suppression of the unwanted signals in different NLTL applications. The filtering method is applied to a nonlinear transmission line frequency multiplier in order to filter the third harmonic. The distributed filtering is also used to suppress the image signal in an NLTL mixer. The proposed filtering method is general and can be applied to other periodic structure as well (such as distributed amplifiers and distributed mixers). For implementing the filtering, compact complementary split ring resonators are proposed and designed for an NLTL frequency doubler