Document Type
Dissertation
Date of Award
Spring 5-31-2002
Degree Name
Doctor of Philosophy in Electrical Engineering - (Ph.D.)
Department
Electrical and Computer Engineering
First Advisor
Richard V. Snyder
Second Advisor
Edip Niver
Third Advisor
Gerald Martin Whitman
Fourth Advisor
Sridhar Kanamaluru
Fifth Advisor
Aly Fathy
Abstract
Using cross-coupled networks of a new concept, transmission zeros were efficiently located in the complex frequency-domain. With this approach, the group delay and attenuation slope of the circuit network can be controlled to get both sharp rejection characteristics and linear phase slopes. In order to achieve this performance, various types of combline filters are suggested. Various simulation tools (commercial linear circuit and E-M simulators), as well as the developed pole-zero locator program, were used to design a new class of cross-coupled networks. In particular, the polezero locator program can be used to extract an equivalent circuit of the topology that is established from ether EM-simulated data or measured data.
A new cross-coupled quasi-elliptic combline bandpass filter is presented, borrowing the distributed implementation of the capacitance (a top surface metalized dielectric block added as an applique to the top of the circuit), which was conventionally used without metalization to enhance the directivity of the microstrip couplers. The required cross coupling value was achieved by changing the substrate thickness, dielectric constant and area of the top surface metallization of the dielectric block. Effectively, an inhomogeneous transmission line was used to achieve source-load direct crosscoupling with at least one additional transmission zero.
The first application presented, is a new type of reflection-type analog phase shifter using tunable short-terminated combline filters (STCL). An asymptotically approached 360-degree total phase shift is obtained, with a large linear range and an insertion loss of less than -1.5 dB over the full phase shift range at 5 GHz. The second approach presented, which is a new concept, is a tunable finite-transmission-zero filter, taking advantage of the unavoidable frequency dependence of each coupling. In order to obtain such a performance, ferroelectric or ferromagnetic stacked substrates are suggested for tuning the extra transmission zeros as well as the center frequency.
Recommended Citation
Shin, Sanghoon, "Theory and design of mixed lumped-distributed cross-coupled filters with applications to linear phase shifter and tunable filters" (2002). Dissertations. 536.
https://digitalcommons.njit.edu/dissertations/536
