Leaky waves have been known for many years in the context of leaky-wave antennas, but it is only within the past dozen years or so that it was realized that the dominant mode on printed-circuit transmission lines used in microwave and millimeter-wave integrated circuits can also leak. Such leakage is extremely important because it may cause power loss, cross talk between neighboring parts of the circuit, and various undesired package effects. These effects can ruin the performance of the circuit, so we must know when leakage can occur and how to avoid it. In most cases, these transmission lines leak only at high frequencies, but some lines leak at all frequencies. However, those lines can be modified to avoid the leakage. This paper explains why and when leakage occurs, and shows how the dominant mode behaves on different lines. The paper also examines certain less well known but important features involving unexpected new physical effects. These include an additional dominant mode on microstrip line that is leaky at higher frequencies, and a simultaneous propagation effect, which is rather general and which occurs when the line's relative cross-sectional dimensions are changed. The final section of the paper is concerned with three important recent developments: (a) the new effects that arise when the frequency is raised still higher and leakage occurs into an additional surface wave, (b) a basic and unexpected discovery relating to improper real modes, which are nonphysical but which can strongly influence the total physical field under the right circumstances, and (c) the important practical issue of how leakage behavior is modified when the circuit is placed into a package.

This paper reviews recent progresses in the research and development of planar photonic band-gap (PBG) structures, also called electromagnetic crystals, for microwave and millimeter-wave applications. Planar electromagnetic crystals are particularly attractive and intensively investigated because of their easy fabrication, low cost, and compatibility with standard planar circuit technology. Two configurations and their applications are described in this paper: a square lattice of holes etched in a ground plane and the recently developed Uniplanar Compact PBG (UC-PBG) structure. Basic properties as well as applications to microwave circuits are reported. These include harmonic tuning in power amplifier, leakage suppression in conductor-backed coplanar waveguide (CB-CPW), realization of planar slow-wave structure, and performance improvement in microstrip filters and patch antennas.

A three-dimensional beam propagation method based on a finite element scheme is described for the analysis of second harmonic generation devices. For the wide-angle beam propagation analysis, the Pade approximation is applied to the differential operator along the propagation direction. In order to avoid spurious reflection from the computational windows edges, the transparent boundary condition is introduced. Numerical results are shown for quasi-phase matched second harmonic generation devices using periodically domain-inverted LiNbO₃ and LiTaO₃ waveguides. The influences of the shape of domain-inverted regions and the inversion width on the conversion efficiencies are investigated in detail.

We present here a study on the propagation characteristics of two-dimensional periodic structures. The method of mode matching is employed to formulate the boundary-value problem in an exact fashion, and a perturbation analysis is carried out to explain the wave phenomena associated with photonic band gap structures. The dispersion curves of 2D periodic medium and 2D periodic impedance surface are investigated in detail.

This report introduces a new approach to the time domain analysis of the magnetostatic wave in ferrite materials. The time domain analysis is carried out by the finite difference time domain (FDTD) method. To include the gyromagnetic properties which is the origin of magnetostatic wave, direct differentiation of magnetic dipole moment equation in time and space domains without any approximation are carried out and is combined with Maxwell's equation under the FDTD method. As a result, the possibilities of the analysis on the magnetostatic wave with the FDTD method are confirmed and the validities of this approach are confirmed by some inspections. In addition, the analyses of the nonlinear characteristics on the magnetostatic backward volume waves (MSBVW) are carried out and clarify the dependance of the space profile on the input power.

Printed transmission lines have been extensively examined so far, but results obtained there are all concerned with the waveguiding conductors with no loss and zero thickness, except very few results. We have recently studied the transmission characteristics of printed transmission lines in detail, when the waveguiding conductors have finite conductivity and thickness, and we have found an unexpected effect that we call a "mode extinction effect. " This effect results in significant changes in the dispersion behavior of the printed-transmission-line fundamental mode. For a critical thickness, it may turn out that such transmission line can not use in open structural configuration, but must always be used by putting into a packaging box. In this paper, we discuss thoroughly this important effect and related results from the standpoints of both the dispersion behavior and the vector field plots. We also show the measured results of the attenuation constant.

IC interconnect transmission line effects due to the characteristics of a silicon substrate and current return path impedances are physically investigated and experimentally characterized. With the investigation, a novel transmission line model is developed, taking these effects into account. Then an accurate signal delay on the IC interconnect lines is analyzed by using the transmission line model. The transmission line effects of the metal-insulator-semiconductor IC interconnect structure are experimentally verified with s-parameter-based wafer level signal-transient characterizations for various test patterns. They are designed and fabricated with a 0.35 µm CMOS process technology. Throughout this work, it is demonstrated that the conventional ideal RC- or RLC-model of the IC interconnects without considering these detailed physical phenomena is not accurate enough to verify the pico-second level timing of high-performance VLSI circuits.

Localization properties of mode waves in an off-diagonally disordered waveguide system are presented. The disorder is introduced by taking spacings between cores to be random variables. Coupled mode equations are transformed into a matrix eigenvalue problem and eigenvalues and eigenvectors are numerically obtained. Correspondences between the natures of modes and the modal density of states are discussed. The system is divided into several sections which behave effectively as isolated systems. Modes in the entire system are a superposition of modes associated with the sections. A section is divided into several elements, which do not only behave apparently as isolated systems but also couple with each other. When an element includes two cores coupled strongly with each other due to a narrow spacing, modes are strongly localized there. The extent of the modes is almost independent of the disorder of the system. In a system with small disorder strongly localized modes can exist. The modes appear outside the propagation constant band of the ordered system composed of identical cores of equal spacing. Modes near the center of the band are extended over a number of elements and have the relatively large extent. Many modes appear near the center of the band and the modal density of states has a sharp peak there.

We first reported the simultaneous-propagation effect that the leaky dominant mode can be present on conductor-backed coplanar strips at the same time as the conventional bound dominant mode. We have investigated here numerically and experimentally this effect in detail. Consequently, we have found that it occurs under a certain condition of structural parameters, and also have verified that it affects circuit performance significantly.

A 20 GHz-band GaAs MMIC receiver module has been developed using 0.15 µm HEMT technology process. It incorporates two front end low noise amplifiers, a double balanced diode mixer, and filters. The RF input frequency ranges 20.1 to 21 GHz and the IF output 1.1 to 2 GHz. Test results show an overall conversion gain of more than 27 dB, and less than a 2.2 dB noise figure. The image-rejection ratio greater than 21 dB has been obtained. The isolation between RF and IF ports is better than 27 dB, and between LO and IF is more than 50 dB.

In this letter, we propose an approximate calculation formula for the resonant frequency of a microstrip antenna with meshed ground plane, which is derived by perturbational technique and is expressed by a simple closed form. The calculated results are in good agreement with FDTD-calculated and measured ones. Therefore, it is confirmed that the proposed formula is valid for approximate evaluation of the resonant frequency of microstrip antenna with meshed ground plane.

A novel K-band MMIC frequency doubler has been developed using resistive series feedback circuit. The doubler exhibits much better D/U ratio, smaller output power variation against ambient temperature and lower power consumption than those of the conventional single-ended doubler. This paper presents the simulation results on the effect of the resistive series feedback by harmonic balance methods. To obtain practical and accurate simulation results, newly developed gate charge model for C_gs and C_gd is introduced. The fabricated result of the proposed MMIC is also demonstrated.

A new output driver design called modified asymmetrical slew rate (MASR) output driver was proposed to reduce the simultaneous switching noise without sacrificing switching speed, for high speed and heavy loading applications. The driving capability of the output driver was designed to sink/source 64 mA current @ V_OL/V_OH = 0.4 V/4.6 V, with 66 pF and 50 Ω loading. When four drivers switch simultaneously, the ground bounce was design to be less than 0.8 V. The performances of the conventional, controlled slew rate (CSR), and MASR output drivers were analyzed by computer simulation. These three types of drivers were implemented with a 0.8 µm CMOS process. The measured ground bounce of the conventional driver is 1.22 V, while the ground bounce of the MASR driver is reduced to 0.72 V. The propagation delays of the conventional and MASR drivers are the same. The performance of the MASR driver is better than that of the CSR driver in all aspects.

In this letter, a simple design of a discrete-time chaos circuit realizing a tent map is proposed. The proposed circuit can be constructed with 13 MOSFET's and 2 capacitors. Concerning the proposed circuit synthesized using switched-current (SI) techniques, the validity of the circuit design is analyzed by SPICE simulations. Furthermore, the proposed circuit is built with commercially-available IC's. The proposed circuit is integrable by a standard CMOS technology.

In this letter, we describe a four thin-film-transistor (TFT) pixel circuit based on hydrogenated amorphous silicon (a-Si:H) technology for the active-matrix organic light-emitting diode (AMOLED) display applications. The circuit uses current-writing mechanism and can automatically adjust the threshold-voltage shifts of both the organic light-emitting diodes (OLEDs) and the TFTs induced by the circuit aging or process variations. Experimental results indicate virtually no variation of the output driving current after long-term bias-temperature-stress (BTS).