Microwave Integrated Circuit Discontinuity Equivalent Circuit

Transmission lines (e.g. microstrip line, stripline, coplanar waveguide (CPW), etc.)are widely used in microwave integrated circuits (MICs) as well as in monolithicmicrowave integrated circuits (MMICs). Analysis of the fundamental discontinuities intransmission lines is of much importance since a complicated circuit is realized byinterconnecting circuit components with transmission line and their line discontinuities.Different circuit models have been developed for different circuit discontinuities before.Such complexity makes interpretation for improved design of a total circuit of manydiscontinuities difficult. Through a careful physical interpretation of the moment method(MoM), a single equivalent circuit model has been constructed to solve many linediscontinuities that are related to the joining of several open-end circuits. This generalcircuit model makes the design of microwave circuits fast and accurate. Via holes providethe connection between lines located in different layers of a multilayered board. A simple,but precise equivalent circuit is required to characterize the via hole including theinterconnect discontinuities.From an existing open-end circuit model, the thesis constructs an alternative open-endcircuit model, that applies to all such line joining discontinuities-for example, step,fight-angle bend and T-junction. The equivalent circuit model is derived under thequasi-static condition after the interpretation of the MoM. Together with transmission linetheory, this single field-based equivalent circuit model is applied for the analysis ofmicrostrip line, stripline, CPW discontinuities and practical microwave components. In thisthesis, most commonly encountered stripline and CPW discontinuities are analyzed, aswell as a low-pass filter, a branch line coupler for stripline and a power divider for CPW. Inaddition, the via hole is modeled as aπ-network of lumped inductance and capacitance,neglecting possible coupling between electric and magnetic fields. The inductance andcapacitance of the via hole can be obtained by the experimental and numerical results.Compared with numerical results, the average errors of S-parameters for stripline andCPW discontinuities are less than 2％within the quasi-static frequency range, while theaverage error of S-parameters is less than 5％for the via hole.