The Smith chart was primarily developed, extended, and refined by Phillip Hagar Smith [1] in a series of works published [2]-[4] between 1939 and 1969. Smith was born in Lexington, Massachusetts, in 1905. He majored in electrical communications at Tufts University and joined the Radio Research Department of Bell Telephone Laboratories (now Bell Labs) in 1928. While there, in around 1930, Smith started work on the diagram that was to become the Smith chart. He submitted the initial version to Electronics Magazine in 1937; the magazine finally published his diagram in 1939 [2]. The MIT Radiation Laboratory started using the chart. In 1940, and in 1944 Smith published a second article that incorporated further improvements, including the use of the chart with either impedance or admittance coordinates. In 1952, Smith was elevated to IEEE Fellow for his contributions to the development of antennas and the graphical analysis of transmission-line characteristics. The first issue of Microwave Journal (1958) published a biography of Smith to acknowledge the importance of his contributions. In 1969, he wrote the book Electronic Applications of the Smith Chart in Waveguide, Circuit and Component Analysis; he retired from Bell Labs in 1970. In 1975, he received the IEEE Microwave Theory and Techniques Society?s Special Recognition in Microwave Applications award for the Smith chart, and in 1994 he was elected to the New Jersey Inventors Hall of Fame.

The paper is describing and presenting the recent advances in the 3D Smith chart representations and applications and then it proposes a new conceptual model for the extended 2D Smith chart based on hyperbolic geometry by mapping the generalized Smith chart in the unit disc using the stereographic projection from a hyperboloid (Poincare disc model).

The paper explains for the first time the visual complex analyisis propeties of the very recently proposed 3D Smith for active and passive circuits. The authors develop their very actual concept with elements of complex analysis applied in the complex plane and in 3D (Riemann sphere). The geometrical properties of the different transfromations of the complex plane are exploited and applied in microwave design.

The mathematical theory of the 3D Smith chart1 unifies active and passive microwave circuit design on the surface of a Riemann sphere. The reflection coefficient plane is mapped stereographically through the South Pole on the surface of a unit sphere. As a result, the classical 2D Smith chart including the passive loads2 is mapped stereographically into the North hemisphere, while the circuits with negative resistance (that are outside the classical planar Smith chart) are mapped into the South one. The East hemisphere is the place of inductive circuits, whereas the West hemisphere hosts the capacitive circuits. Meantime, the Greenwich meridian is the locus of pure resistive circuits (see Figure 1, where the constant resistance r and reactance x circles are drawn in blue and red, respectively). The 3D Smith chart differs from previous attempts4 to generalize the planar 2D Smith chart in a fundamental way: the way in which infinity is treated. The preceding theories fail to merge the active and passive worlds in a simple and rigorous manner, since they propose an empirical solution to map an infinite region into a finite surface. These approaches turned into complicated transforming equations, making the visual and intuitive interpretation of microwave problems very difficult. In this article, how the 2D and 3D Smith charts deal with the infinite regions are first described. Next, the advantages of using the 3D Smith chart to represent both active and passive loads are illustrated with two examples: the stability circles of an amplifier and the impedance of a microwave oscillator.

This paper presents a study of the dispersion of the casting replication process using SU-8 master structures. Samples of master structures and replicated microfluidics test structures are fabricated. The resulted master and replicated structures are measured. By experimental observations and by statistical analysis it is shown that the casting replication method has the same dispersion as the fabrication process of the used master structures.

This letter proposes a spherical 3-D Smith Chart suitable for representing both active and passive microwave circuits. Using the mathematical concept of the Riemann sphere, the extended reflection coefficient plane is transformed into the surface of the unit sphere. Since the proposed Smith Chart compiles the whole complex plane, all possible loads are included. A simple graphic tool is thus obtained that successfully unifies active and passive circuits. In addition, lossy lines with complex characteristic impedances can also be represented. The letter presents the 3-D Smith Chart, provides its main governing equations, and also enumerates its more important properties.

This paper describes the design, manufacturing and experiments of a lumped element band pass filter in a new topology. The design starts from a second order capacitive coupled resonator topology. An additional series inductor is inserted in the filter classical topology, for shifting two transmission zeros on the real frequency axes in the filter's band stop, to improve the high frequency response. Design equations for the new band stop resonance frequency are presented together with the analysis of the correspondence between the band pass and band stop attenuation vs. the quality factor of the shunt and series inductors used. The filter is supported on a 6.4μm thin dielectric membrane, and is manufactured using silicon micromachining, in CPW technology. Measurements illustrated a minimum 2.75dB insertion loss at 5.5GHz in the band pass, and more than 40dB attenuation, at 8GHz.

The present paper analysis the suitability of using the polymer casting replication method for the fabrication of microfluidic components. As test structure it is used a passive micromixer with a complex geometry that contains tight angles and several curvatures. There are test three types of masters for the replication, made in silicon, SU-8 and copper.

This paper presents the layout and the technological steps for an interdigitally integrated capacitor used for gas detection. Silicon micromachining technology is applied for manufacturing the sensor substrate. The sensitive layer used is phthalocyanine (Pc) deposed by EDL (evaporated dyes layers technique). Many solutions were found using the phthalocyanine derivatives deposition technique. Considering the different sensitivities of phthalocyanines derivatives, we obtained different gas sensors. The copper phthalocyanine (Cu Pc) and nickel phthalocyanine (Ni Pc) have been investigated for NO/sub x/ detection. The measurement of sensors for NO/sub x/ and NH/sub 3/ detection are presented as concentration versus impedance. The microsensor testing structures deposited with phthalocyanines were investigated by impedance measurements in a vacuum chamber controlled by a gas analyzer. The measurements were made at room temperature but a medium temperature is applied (< 200/spl deg/C) after measurement, for cleaning the material in order to reuse the sensor. The sensor is integrated, MOS compatible, cheap, easy to use and has low power consumption.

We present the investigation of different types of silicon-compatible optical waveguides and the possibility to use them in an opto-mechanical pressure sensor. Silicon-based integrated optics appears as an attractive domain of applications for micromachining and allows the development of micro-opto-mechanical systems (MOEMS). Optical systems integrated on silicon are of special interest because of their process compatibility with CMOS technology. The work is focused on the fabrication of an opto-mechanical pressure sensor based on a Mach–Zehnder interferometer, integrated with photodiodes and diaphragms. Micromechanical, optical and microelectronic structures are fabricated on the same silicon substrate. The mechanical part is a cascade of three diaphragms, made by wet anisotropic etching of the substrate. For optical waveguides we experimented with different materials: Si3N4, SiON, polyimides, SiC, and amorphous silicon. We investigated the optical properties of these materials, technological processes and the possibility to integrate them in a microsystem.

A microbridges software simulation has been made using "CoventorWare 2001.3", from Coventor Inc. Within this program, we used the piezoresistive module. The microbridges are made of silicon, and the piezoresistive part is the device itself. The resonant microbridges change their resistance when the gas-sensitive layer adsorbs gas molecules from the environment. The simulations have been made for three different dimensional cases of the bridges length, in order to determine the most sensitive design model. The results have shown a good electrical current shift, of up to 20% for 22 mA up to 38 mA currents.

A capacitive differential pressure sensor which is CMOS compatible is designed and realized. The device consists of a variable capacitor made by silicon bulk and surface micromachining. The upper electrode is a diaphragm in a sandwich of polyimide and metal. The bottom electrode is placed on a silicon substrate and is formed by Cr/Au deposition. The sensor has a 5 /spl mu/m air gap as a dielectric. It is made from monocrystalline silicon by means of micromachining methods. It has an area of 800/spl times/800 /spl mu/m and a thickness of about 7 /spl mu/m. The sensor can be integrated on one chip with a pre-amplifier circuit and is designed and simulated using the MEMCAD 4.8 software. In MEMCAD, we designed the 2D and 3D models, according with the technological manufacturing processes. We simulated the capacitance of the sensor depending on the applied relative pressure. A sensitivity /spl Delta/C/C of about 60% is achieved for a differential pressure of 1 atm. The results of the analysis show that the sensor can be used at relative pressures between 0 and 1.6 atm. The scale of pressures can be enlarged easily by increasing the air gap or by changing the thickness of the polyimide diaphragm. The manufacturing of the device is briefly described, but the focus lies primarily on the design and simulation of the sensor.

This paper presents the results from an investigation of the chemical anisotropic etching of silicon in the following solution: KOH 4.5M, K-3[Fe(CN)(6)] 0.1M, K-4[Fe(CN)(6)]. 3H(2)O 0.1M, KNO3 0.1M and complexant added. The reaction mechanism, the etch rate and the roughness are analysed.

This paper presents the results obtained in silicon hillock elimination using alkaline solutions: KOH, NaOH, LiOH·H2 O with complexant added. The complexant used is Azo calix[4]arene. The alkaline solutions are compared and analysed with and without complexant added from the point of view of hillocks, and the behaviour of the solutions is explained using the theory of molar conductivity. The results allow us to use the alkaline solutions and the organic complexant to monitor the etching process and to obtain a smooth silicon surface, almost free of hillocks

This paper present the results from the investigation of the chemical anisotropic etching of single-crystal silicon in the following solutions: KOH, K3[Fe(CN)6] 0.1M, K4[Fe(CH)6] 3H2O 0.1M, KNO3 0.1M and/or complexant added. The complexants added in KOH solution were: Calix(4)arenes, Phenols and Ether Dibenzo 18 Crown 6. The result using also NaOH or LiOH H2O and complexants are presented. The reaction mechanism and the hillocks formation and elimination are analyzed. The results allow us to use the redox system and/or the organic complexants, to monitor the etching process, to obtain a smooth silicon surface, almost free of hillocks, to utilize the usual mask material resistant at the new etchants.

The gate arrays option in manufacturing ASIC CMOS is conditioned by the possibility of satisfying small orders requirements of small- and medium-sized electronic equipment manufacturing companies, in a large variety of circuits. The authors present contributions in optimizing critical processes for an n-well CMOS polysilicon gate arrays technology. Technological achievements were proved by measurements on the test devices but mainly by array chip fabrication. There were manufactured chips for specialized circuits intended for telephone switching equipment

This paper presents the results of the study and experiments of the chemical anisotropic etching of silicon in a complexant alkaline system (KOH 4.5 M and complexants added). The great results obtained using calix[4]arene like complexant make necessary the study of the mechanism of the silicon etch rate increasing and of the roughness minimizing. A new macrocyclic complexant (azocalix[4]arene) and indicator of pH for silicon etching solution, the etch rate and the roughness are analysed. The complexant alkaline system for anisotropic etching of silicon is an absolutely original idea of the authors.

A new type of integrated thermal flow sensor containing two symmetrical measuring channels is presented. The structure permit optimisation of flow sensing in applications with transient velocity, temperature or conductivity profiles in the fluid and has improved sensitivities for small temperatures differences above ambient, necessary for medical applications. Analysis is made for fluid flow and heat transfer using analytical and FEA technics. Technological implementation optimises the compensation of the internal stresses in the suspended structures and passivation of the sensor structure for work in aggressive media. Electronic interfaces for processing are derived for development of a fully integrated variant of the sensor.