Two-port Subnetworks Research Articles

Reflectionless Filter Structures

This paper expands on the previously described reflectionless filters - that is, filters having, in principle, identically-zero reflection coefficient at all frequencies - by introducing a wide variety of new reflectionless structures that were not part of the original publication. In addition to extending the lumped-element derivation to include transmission line filters, this is achieved by the introduction of a novel method wherein the left- and right-hand side stop-band terminations are coupled to each other using a two-port sub-network. Specific examples of the sub-network are given which increase the stop-band attenuation per filter cell and steepen the cutoff response without disrupting the reflectionless property or increasing the insertion-loss in the pass-band. It is noteworthy that a common feature of all the structures derived by these methods is that most, if not all, of the reactive elements are of equal normalized value. This greatly simplifies the tuning requirements, and has facilitated their implementation as monolithic microwave integrated circuits (MMICs). A number of examples of MMIC reflectionless filters constructed in this way are presented and their results compared to the theory.

Closed-Form Expressions for the Equivalent Circuit Model of Square-Waveguide T-Junctions and Its Application in Ortho-Mode Transducer Design

In this paper, closed-form expressions for the equivalent circuit model of square-waveguide T-junctions are presented. The square-waveguide T-junction is first modeled as a generalized admittance matrix and then reduced to a general five-port network. It is theoretically seen that the general five-port network can be simplified as a combination of a two-port subnetwork and a three-port subnetwork through the mode-matching analysis. Accurate closed-form expressions are derived with proper approximations to calculated the admittance parameters of these two subnetworks. A short-circuited branch ortho-mode transducer is then designed in a circuit simulator using the proposed equivalent circuit model. Measured results exhibit an excellent agreement with those from circuit simulation.

Switched-current wave filters based on lossy integrators

A new method for designing switched-current wave filters is presented. The LC ladder prototype filter is split into two-port subnetworks and their wave equivalents are obtained using the scattering parameters description. The elementary building block is chosen to be the wave equivalent of an inductance in series-branch, which is constructed from a lossy integrator configuration. The equivalents of the other reactive elements in series or shunt-branch can be readily obtained by interchanging the outputs of the elementary block and/or using inverters. Simulation results show that the sensitivity of the derived filter configurations, to the MOS transistor parameters mismatch, was minimised in comparison with the already known switched-current wave filter topologies.

Equivalent matrix parameter functions for two-port sub-networks of non-uniform thin-film Y-Z-KY structure

The four-terminal non-uniform distributed-parameter (NUDP) Y-Z-KY structure may be physically realised in thin-film integrated circuitry. This four-terminal Y-Z-KY structure can produce at most thirty two unique non-redundant two-port subnetworks. To study the performance characteristics of these two-port sub-networks one invariably requires their matrix parameters. This paper presents for the first time the equivalent matrix parameter functions (EMPF's) of all these thirty two sub-networks. Using these EMPF's one can express any matrix parameter and network function associated with a two-port. Based on the results of this paper, a large number of two-port subnetworks of the exponential thin-film Y-Z-KY structure are recently studied for their low-pass, high-pass, band-pass, band-rejection, gain equalizer and phase equalizer circuit characteristics for applications in communication systems.

A new frequency independent attenuator in distributed multilayer thin film microsystem : H. R. Singh. Microelectron. Reliab.23 (2), 379 (1983)

This paper shows that one may find a two-port subnetwork of the exponential distributed parameter (DP) Z-Y-KZ micro-circuit whose open-circuit voltage and short-circuit current ratio-transfer functions are exactly the same as those of another two-port subnetwork of the exponential (DP) Y-Z-KY micro-circuit. There are in total 28 such unique non-redundant two-port subnetworks of the exponential Z-Y-KZ structure which have their counterparts produced by the exponential Y-Z-KY micro-circuit. The results are given in a table. This information is intended to eliminate the duplicacy of time-consuming labour involved in the analyses of these subnetworks obtainable from the exponential Z-Y-KZ and Y-Z-KY structures in view of recent interest in the performance characteristics of such subnetworks.

Two-port subnetworks of exponential distributed parameter Z-Y-KZ and Y-Z-KY micro-circuits with similar transfer functions

This paper shows that one may find a two-port subnetwork of the exponential distributed parameter (DP) Z-Y-KZ micro-circuit whose open-circuit voltage and short-circuit current ratio-transfer functions are exactly the same as those of another two-port subnetwork of the exponential (DP) Y-Z-KY micro-circuit. There are in total 28 such unique non-redundant two-port subnetworks of the exponential Z-Y-KZ structure which have their counterparts produced by the exponential Y-Z-KY micro-circuit. The results are given in a table. This information is intended to eliminate the duplicacy of time-consuming labour involved in the analyses of these subnetworks obtainable from the exponential Z-Y-KZ and Y-Z-KY structures in view of recent interest in the performance characteristics of such subnetworks.

Signal flow graph approach to active RC simulation of LC ladder filters

Abstract A simple method is reported for the simulation of doubly resistively terminated lossless ladders by means of active RC networks. The method is based on a proper matrix description of the two-port subnetworks, into which the passive ladder is partitioned. Through the use of signal flow graph concepts, known ladder simulating active networks as well as new ones can be obtained. An example of an all integrator canonic ‘active bandpass ladder’ is also given.