Exact formulas for wave impedance and propagation constants ofhomogeneous, lossy dielectric and/or magnetic materials

Calculations of propagation constants for lossy materials are performed under the approximations of low loss (or high conductivity). To improve the understanding and better predict the analysis of such materials, exact formulation for wave impedance and propagation constants of homogeneous, lossy, dielectric/magnetic materials are proposed. Formulation is based on dielectric and/or magnetic loss tangent of the material     

CAD models for multilayered substrate interdigital capacitors

Conformal mapping-based models are given for interdigital capacitors on substrates with a thin superstrate and/or covering dielectric film. The models are useful for a wide range of dielectric constants and layer thicknesses. Capacitors with finger numbers n⩾2 are discussed. The finger widths and spacing between them may be different. The results are compared with the available data and some examples are given to demonstrate the potential of the models     

Design of broad-band lumped-element baluns with inherent impedance transformation

This paper reports on a novel lumped balun topology, the second-order lattice balun, with broad-band performance. The design is based on synthetic transmission lines operating as impedance transformers. The characteristic impedance of the synthetic transmission lines may be chosen to obtain inherent impedance transformation. An analytical investigation results in closed formulas for optimum performance over a given bandwidth. It is shown that it is possible to design for equal ripple in amplitude balance and input reflection coefficient. The phase balance is theoretically perfect over the entire bandwidth. The concept is experimentally validated by a 1-GHz prototype fabricated with surface mounted chip components. It exhibits an amplitude balance better than 0.5 dB and a phase balance better than /spl plusmn/8/spl deg/ over an octave bandwidth. The effective area of the prototype is 7 /spl times/ 9 mm/sup 2/.     

Composite right/left handed transmission line phase shifter using ferroelectric varactors

A composite right/left handed (CRLH) transmission line (TL) phase shifter, using ferroelectric (Ba/sub 0.25/Sr/sub 0.75/TiO/sub 3/) varactors as tunable element, is presented for the first time. It is theoretically and experimentally demonstrated how the unique features of CRLH TLs, enables a differential phase shift with flat frequency dependence around the center frequency. The experimental prototype is a coplanar design integrated on a high resistive Si substrate. It includes four CRLH T-unit cells and has a physical length of 3850/spl mu/m. The ferroelectric varactors are realized in parallel plate version. Under 15-V dc bias applied over each varactor, the differential phase shift is flat around 17GHz and has an absolute value of 50/spl deg/.     

Optimal parameter extraction and uncertainty estimation in intrinsic FET small-signal models

Analytical expressions for the relative sensitivities in the parameters of a standard intrinsic FET small-signal model with respect to deviations in the measured S-parameters are derived. This enables, in combination with a measurement uncertainty model, the model parameter uncertainties to be studied versus frequency. As a result, optimal, minimum uncertainty, parameter extraction can be performed independent of the bias voltage and without prior knowledge about the device frequency behavior, thus making it suitable for implementation in automatic multibias extraction programs. The derived sensitivities are furthermore used to analytically calculate the uncertainty in the S-parameter response of the extracted model in terms of the uncertainties in either the parameters or the measurement it was extracted from.     

Analytic approximation for open-end capacitance in symmetriccoplanar-strip waveguides

Conformal mapping and the partial capacitance technique are used to derive simple and accurate closed form approximations for the open-end capacitance in a symmetric coplanar-strip waveguide