A new defected ground structure (DGS) for the microstrip line is proposed in this paper. The proposed DGS unit structure can provide the bandgap characteristic in some frequency bands with only one or more unit lattices. The equivalent circuit for the proposed defected ground unit structure is derived by means of three-dimensional field analysis methods. The equivalent-circuit parameters are extracted by using a simple circuit analysis method. By employing the extracted parameters and circuit analysis theory, the bandgap effect for the provided defected ground unit structure can be explained. By using the derived and extracted equivalent circuit and parameters, the low-pass filters are designed and implemented. The experimental results show excellent agreement with theoretical results and the validity of the modeling method for the proposed defected ground unit structure.

A design of the low-pass filter using the novel microstrip defected ground structure

Wave digital filters (WDFs) are modeled after classical filters, preferably in lattice or ladder configurations or generalizations thereof. They have very good properties concerning coefficient accuracy requirements, dynamic range, and especially all aspects of stability under finite-arithmetic conditions. A detailed review of WDF theory is given. For this several goals are set: to offer an introduction for those not familiar with the subject, to stress practical aspects in order to serve as a guide for those wanting to design or apply WDFs, and to give insight into the broad range of aspects of WDF theory and its many relationships with other areas, especially in the signal-processing field. Correspondingly, mathematical analyses are included only if necessary for gaining essential insight, while for all details of more special nature reference is made to existing literature.

Wave digital filters: Theory and practice

An ultrawideband 3.1-10.6-GHz low-noise amplifier employing an input three-section band-pass Chebyshev filter is presented. Fabricated in a 0.18-/spl mu/m CMOS process, the IC prototype achieves a power gain of 9.3 dB with an input match of -10 dB over the band, a minimum noise figure of 4 dB, and an IIP3 of -6.7 dBm while consuming 9 mW.

An ultrawideband CMOS low-noise amplifier for 3.1-10.6-GHz wireless receivers

Preface. Introduction, Fundamental Concepts, and Definitions. Solid-State Device Modeling. Harmonic-Balance analysis. Volterra-Series and Power-Series Analysis. Balanced Circuits. Diode Mixers. Diode Frequency Multipliers. Small-Signal Amplifiers. Power Amplifiers. Active Frequency Multipliers. Active Mixers. Oscillators. Index.

Nonlinear Microwave and RF Circuits

Immittance, transfer, and scattering characteristics are studied for acoustic surface wave transducers of the interdigital electrode form. Linear network models are used to represent the transducer as a chain of identical three-ports which are acoustically in cascade but electrically in parallel. Transducer operation at acoustic synchronism is described theoretically and compared to current experimental data for transducers operating at 100 MHz and fabricated on lithium niobate. Favorable lithium niobate configurations for efficient, broad-band transducer operation are given. Scattering characteristics as a function of electric load are discussed. Low values of acoustic reflection loss are predicted theoretically and observed experimentally when the electric load and transducer capacitance are in resonance. The frequency dependence of transducer radiation immittance is studied, and the response is found to be analogous to the response of an endfire antenna array.

Analysis of Interdigital Surface Wave Transducers by Use of an Equivalent Circuit Model

Microwave Filters, Impedance-Matching Networks, and Coupling Structures

The synthesis (as opposed to analysis) of multilayer dielectric films as antireflection coatings over any specified frequency band has not been attempted before. The similarity with transmission lines, which can be synthesized as multisection quarter-wave transformers to minimize reflection over any prescribed frequency band, is utilized by applying recently developed synthesis procedures for quarter-wave transformers to the synthesis of multiple antireflection films. [ See O. S.
	 Heavens
	 
	, Optical Properties of Thin Solid Films ( Academic Press, Inc., New York, 1955); and P. J.
	 Leurgans
	 
	, J. Opt. Soc. Am.41, 714 ( 1951).] A brief review of network synthesis is given, leading up to the synthesis of quarter-wave transformers and multilayer films. Numerical tables are presented in this paper from which antireflection coatings of up to four layers can be designed by interpolation. The design procedure (synthesis) described herein leads to the best possible antireflection films, but demands precisely controlled materials with certain refractive indices. It is hoped that this paper will help to promote the development of such materials, and will encourage opticists to try experimentally for the optimum performances possible in theory.

Synthesis of Multiple Antireflection Films over a Prescribed Frequency Band

Quarter-wave transformers are widely used to obtain an impedance match within a specified tolerance between two lines of different characteristic impedances over a specified frequency band. This paper gives design formulas and extensive tables of designs, most of which were especially derived so that an integrated account could be presented for the first time. Numerous examples are given. Only homogeneous, synchronous transformers and filters are included in this paper, but a short bibliography on related topics is appended. The theory is also applied to band-pass filters, by showing how to convert quarter-wave transformers into half-wave filter prototypes. The theoretical and numerical results presented are applicable to the design of impedance transformers, direct-coupled cavity filters, short-line low-pass filters, optical antireflection coatings and interference filters, acoustical transformers, branch-guide directional couplers, TEM-mode coupled-transmission-line directional couplers, and other circuits. These applications have been or will be dealt with in separate papers; this paper gives the basic theory and some of the numerical data required for these applications.

Stepped-Impedance Transformers and Filter Prototypes

Direct-coupled resonator filters in transmission line are discussed. The resonators consist of sections of transmission line coupled either by series capacitances or shunt inductances. Over narrow frequency bands, such filters show characteristics similar to those of lumped-constant filters and their design is straightforward. The design of direct-coupled resonator filters over wide (as well as narrow) frequency bands is presented here using the quarter-wave transformer as a prototype circuit. Several numerical examples (with fractional bandwidths between 10 per cent and 85 per cent) are worked out to illustrate the method. It is shown that the response can be improved by optimizing the line impedances.

Direct-Coupled Cavity Filters for Wide and Narrow Bandwidths

In most microwave systems the signal frequency has to be transmitted and guided from one place to another with the minimum of attenuation, while guarding against unwanted frequencies by keeping them out with bandpass filters, which pass only the signal frequency. While the common types of bandpass filters do an adequate job for most applications, they suffer from some disadvantages in particular situations. It may, for instance, happen that some one interfering frequency is particularly strong and special measures have to be taken to suppress it; or that a limited number of frequencies are being generated in a frequency generator system, but these frequencies have to be kept apart and pure. In those cases, a bandpass filter, which discriminates against all frequencies outside the passband, will not be as efficient as one or more bands top filters which discriminate especially against the strongest unwanted frequencies,

Leo Young

Papers

Microwave Filters, Impedance-Matching Networks, and Coupling Structures

Synthesis of Multiple Antireflection Films over a Prescribed Frequency Band

Stepped-Impedance Transformers and Filter Prototypes

Direct-Coupled Cavity Filters for Wide and Narrow Bandwidths

Microwave Band-Stop Filters with Narrow Stop Bands