Q factor

This paper proposes a new differential topology that features a stacked multiloop inductor. Comparative studies of stacked one-to four-loop spiral inductors with and without patterned ground shields (PGSs) for silicon-based radio-frequency integrated circuits (RFICs) were conducted, and lumped-element circuit models were developed for these inductors. The partialelement equivalent-circuit method that can accurately analyze mutual inductive couplings among different spirals in these multiloop geometries was employed for capturing the frequencydependent inductances and resistances of inductors at low frequencies. A good agreement between numerical results and measurements is obtained. It is demonstrated that a stacked multiloop spiral inductor with differential topology and PGS has a larger inductance and a higher Q-factor as compared with the same inductor without differential topology and PGS. This hybrid methodology could provide a promising technique for developing new silicon-based passive devices used in RFICs.

A novel optical technique is proposed for the characterization of MEMS resonators. The proposed technique is based on measuring the response of the resonator (resonance frequency and quality factor) optically, which eliminates the electrical parasitic effects. The proposed technique was applied to a comb-drive resonator and the obtained results show good agreement with the standard electrical technique with 2-5% deviation in the resonance frequency and 2-10% in the quality factor.

In this paper, a new cross-coupled microstrip filter based on the grounded patch resonators is designed, fabricated and measured. Coupling characteristics of three basic coupling structures encountered in this class of filters are investigated using full-wave electromagnetic simulations, and the design curves for coupling coefficients and the external quality factor are presented. As the demonstration, a fourth order cross-coupled filter of this type is designed, fabricated and measured.

SUMMARY A batch-compatible, post-fabrication annealing technique based upon filament-like heating of microstructures is demon-strated as an effective means for trimming the reSonance fre-quencies (fa's) and increasing the quality factors (Q's) of surface-micromachined, ...

In this paper, high quality factor frequency (~27MHz and ~54MHz), lateralthin-film piezoelectric-on-silicon resonators ar particle mass sensors. Using an aerosol partic sensitivities of -4.2Hz/pg and -42Hz/pg respectively which confirms the benefits of frequency resonators given the quality factor i These results are in good agreement with th simulated values. Our work suggests the TPoS easily integrated, low-loss platform for applications.

In the present paper we discuss antenna miniaturization using magneto-dielectric substrates. Recent results found in the literature reveal that advantages over conventional dielectric substrates can only be achieved if natural magnetic inclusions are embedded into the substrate. This observation is revised and the physical background is clarified. We present a detailed discussion concerning magnetic materials available in the microwave regime and containing natural magnetic constituents. The effects of magnetic dispersion and loss are studied: constraints on the microwave permeability are used to estimate the effect of magnetic substrates on the achievable impedance bandwidth. Microwave composites filled with thin ferromagnetic films are considered as a prospective antenna substrate. We calculate the impedance bandwidth for a λ/2-patch antenna loaded with the proposed substrate, and challenge the results against those obtained with conventional dielectric substrates. It is shown that the radiation quality factor is strongly minimized with the proposed substrate even in the presence of realistic losses. Estimates for the radiation efficiency are given as a function of the magnetic loss factor.

In this study the characterization of an aluminum nitride (AlN) double ended tuning fork (DETF) fabricated on a layer of silicon dioxide (SiO 2 ) is presented. The positive temperature coefficients of SiO 2 are used to achieve zero TCF for radio frequency (RF) Lamb wave resonators. This paper shows the possibility to integrate temperature compensated Lamb wave resonators with DETF-based devices on a single chip. The DETF resonates in a quasi-in-plane mode shape with a Q-factor of 578 in air and 3028 in vacuum. Through a laser Doppler velocity (LDV) measurement we also show that, due to the biomorph nature of the structure and the angle of the side walls, the motion of each tine of the DETF is a combination of in-plane bending, out-of-plane bending and torsional motion around the beam main axis.

To what extent are firms kept out of a market by patents covering related technologies? Do patents held by potential entrants make it easier to enter markets? We estimate the empirical relationship between market entry and patents for 27 narrowly defined categories of software products during the period 1990-2004. Controlling for demand, market structure, average patent quality, and other factors,

We present a method of making low-loss split-ring resonators (SRRs) for microfluidic sensing at microwave frequencies using silver-coated copper wire. We show that a simple geometric modification and the use of square cross-section wire give greater electric field confinement in the capacitive region of the resonant sensor. We use a combination of theoretical analysis, finite-element simulations, and empirical measurements to demonstrate the subsequent increases in the sensitivity of these SRRs for complex permittivity measurements of some common solvents.

This paper presents the design and optimisation of a very high quality (Q) factor inductor using MEMS technology for 10 GHz to 20 GHz frequency band. The effects of various parameters of a symmetric inductor structure on the Q-factor and inductance are thoroughly analysed. The inductor has been designed on silicon-on-sapphire (SOS) substrate because it offers superior characteristics of low

A novel method for designing multiband bandpass filters has been proposed in this paper. Coupling structures with both Chebyshev and quasi-elliptic frequency responses are presented to achieve dual-and triple-band characteristics without a significant increase in circuit size. The design concept is to add some extra coupled resonator sections in a single-circuit filter to increase the degrees of freedom in extracting coupling coefficients of a multiband filter and, therefore, the filter is capable of realizing the specifications of coupling coefficients at all passbands. To verify the presented concept, four experimental examples of filters with a dual-band Chebyshev, triple-band Chebyshev, dual-band quasi-elliptic, and triple-band quasi-elliptic response have been designed and fabricated with microstrip technology. The measured results are in good agreement with the full-wave simulation results.

This paper presents the design, fabrication, and characterization of a microwave resonator as a tool for concentration measurements of liquid compounds. The sensing device is a rectangular waveguide cavity tuned at 1.91 GHz, which exploits the fundamental TE 101 mode in a transmission-type configuration. The coupling structure is optimized by means of a finite element code so as to achieve a high Q-factor. According to the type of substance inside the mixture, its concentration is conveniently related to changes of the S 21 scattering parameter (transmission coefficient) in terms of: 1) resonance frequency; 2) 3-dB bandwidth; and 3) amplitude at the resonance frequency. Experimental tests on liquid solutions in controlled conditions are presented to evaluate the performance of the device.

Chromatic dispersion is very serious issue for communication engineers while designing a wave division multiplexing for optical communication. In the present scenario there is a increasing demand of high speed internet which require more capacity and more bandwidth. The effect of chromatic dispersion can be reduced by compensation technique. [1, 2] The chromatic dispersion also has inverse relationship with FWM. In this paper we used post dispersion compensation along with the fiber Bragg grating to reduce the effect of chromatic dispersion. Also we can compare the Bit error rate at different power levels 5 db, 10 db and 20 db while the length of fiber is fixed. After simulation it is proven that bit error rate is a function of input power level. The pulse broadening is a function of length of fiber which has been shown in this work When the BER increases quality factor decreases and overall fiber optic system degraded. In this paper we also prove that the BER is also a function of Length of Fiber. As the fiber length increases BER also increases. The whole simulationn is performed by Optisystem simulation software. Also by examine the eye diagram it is clear that link performance is improved by using dispersion compensation.

As much of the work of service employees is supported by IT, the quality of the service often depends on how the technology is used. Most employees only use a fraction of the functionality available on their desk-top. This may also depend on their personality. We performed research on the relationship of personality and technology acceptance.

Thermal noise is generated naturally by thermal agitation of electrons in a conductor commonly found in opto-electronic devices. The fact that the optical medium is totally immune to noise does not exclude its occurrence in receiver parts. In communication, thermal noise has a major influence to the quality of the receiver. The lower the thermal noise the higher and more expensive is receiver sensitivity. This paper starts with a tutorial on thermal noise in common communication technologies. The major contribution factor to thermal noise power is also discussed analytically. For more comprehensive view, the includes a study on thermal noise effects network performance in terms of BER, maximum Q-factor, eye height and maximum distance. The fiber-to-the-home network is used as a test field to study the impact of two different values of thermal noise on network parameters. At the end of this paper, thermal noise minimizing techniques are also listed.

As much of the work of service employees is supported by IT, the quality of the service often depends on how the technology is used. Most employees only use a fraction of the functionality available on their desk-top. This may also depend on their personality. We performed research on the relationship of personality and technology acceptance.

Dielectric microspheres, with sizes on the order of several wavelengths, support high-quality whispering gallery (WG) modes and provide nonresonant focusing of light into tiny spots termed nanoscale photonic jets. In this chapter, we review properties of more complicated multiple-cavity systems that are formed by microspheres assembled in chip-scale structures. The resonant optical properties of such systems can be engineered on the basis of tight-binding WG modes in photonic atoms. In practical systems of coupled cavities, the optical transport properties are strongly influenced by disorder effects, leading to scattering, localization, and percolation of light. The desirable tight-binding properties require selecting more uniform spheres, which can be achieved by novel methods based on using sizeselective radiative pressure. Due to controllable dispersions for photons, collective emission and absorption, and enhanced light-matter coupling, such structures can be used for developing coupled arrays of microlasers, ultracompact high-resolution spectrometers, and sensors. The nonresonant properties of such systems are connected through subwavelength focusing of light in chains and arrays of microspheres that can be used in a variety of biomedical applications including ultraprecise laser tissue surgery.

Compact optical channel dropping filters incorporating side-coupled ring resonators as small as 3 m in radius are realized in silicon technology. Quality factors up to 250, and a free-spectral range (FSR) as large as 24 nm are measured. Such structures can be used as fundamental building blocks in more sophisticated optical signal processing devices.

Methods to determine resonant cavity Q-factor from vector network analyser reflection data are often quite complex. This study presents a simple method which makes use of two least squares algorithms applied sequentially. Firstly, a circle is fitted to the data, which is then projected onto a linear frequency scale using the Ginzton technique. A straight line is fitted to the projected data, and the loaded Q-factor and the resonant frequency are obtained from the line coefficients. The method has been tested on both synthetic and experimental data, and compared with the Kajfez QZERO software, and the results are shown to be accurate to a fraction of 1%.

A 160-Gb/s (4 40 Gb/s) return-to-zero differential quadrature phase-shift keying polarization-division multiplex transmission is demonstrated with 15 6 dB in one of eight 100-GHz-spaced wavelength-division-multiplex channels after 230 km of fiber. Residual chromatic dispersion (CD) is equalized by a thermally tunable CD compensator for the 192.5-THz channel. Polarizations, in-phase and quadrature data channels are demultiplexed using a LiNbO 3 -based automatic polarization control and a 1-bit interferometer, respectively. Index Terms-Differential quadrature phase-shift keying (DQPSK), polarization-division multiplex (PolDM), tunable chromatic dispersion (CD) compensation, wavelength-division multiplex (WDM).

A Fabry-Perot resonator operating at 39 GHz, with two pairs of quarter-wavelength single-crystal quartz Bragg reflectors has been realized. For the length of 98.26 mm, its Q-factor is about 560,000, which is 4.3 times better than for the same resonator without Bragg reflectors. Rigorous finite-difference frequency-domain analysis has been applied to the problem and is compared with simplified semi-analytical solutions. Good agreement between theoretical and experimental resonant frequency and Qfactors has been obtained. Thermal compensation of the resonant frequency of the Fabry-Perot has been proposed employing rods and cylinders made of metals with different thermal expansion coefficients.

The paper reviews several expressions for high-frequency winding resistance of inductors proposed by several authors and compares the theoretical predictions calculated from these expressions with experimental results. It identifies the expressions that yield the most accurate prediction of the winding high-frequency resistance. The comparison shows that the method proposed by Dowell accurately predicts the ac resistance if the winding contains less than three layers. The methods proposed by several other authors accurately predict the high-frequency resistance only in certain frequency ranges. In addition, these expressions yield inaccurate results for the inductor quality factor. One expression, however, accurately predicts both the high-frequency winding resistance and the quality factor of inductors over a wide frequency range from the dc to the first resonant frequency. The paper concludes with a simple and accurate circuit model describing the frequency behavior of inductors.

Shooting, finite difference, or harmonic balance techniques in conjunction with a damped Newton method are widely employed for the numerical calculation of limit cycles of (free-running, autonomous) oscillators. In some cases, however, nonconvergence occurs when the initial estimate of the solution is not close enough to the exact one. Generally, the higher the quality factor of the oscillator the tighter are the constraints for the initial estimate. A 2-D homotopy method is presented in this paper that overcomes this problem. The resulting linear set of equations is underdetermined, leading to a nullspace of rank two. This underdetermined system is solved in a least squares sense for which a rigorous mathematical basis can be derived. An efficient algorithm for solving the least squares problem is derived where sparse matrix techniques can be used. As continuation methods are only employed for obtaining a sufficient initial guess of the limit cycle, a coarse grid discretization is sufficient to make the method runtime efficient.

A circuit which can function both as quadrature oscillator and as a universal biquad filter (low-pass, high-pass, band-pass, band-reject and all-pass functions) is introduced in this paper. Working as quadrature oscillator, the oscillation condition and oscillation frequency can be adjusted independently with the input bias currents. Functioning as a universal biquad filter, the quality factor and natural frequency can be tuned orthogonally via the input bias currents. The proposed circuit can work as either a quadrature oscillator or a universal biquad filter without changing circuit topology. The proposed circuit description is very simple, consisting of merely 2 current controlled current conveyor transconductance amplifiers (CCCCTAs) and 2 grounded capacitors. Without any external resistors and using only grounded elements, this circuit is thus suitable for IC architecture. The PSPICE simulation results are depicted, and the given results agree well with the theoretical anticipation. The maximum power consumption is approximately 3.78mW at ±1.5V power supplies.

A novel design for a thin frequency selective surface (FSS) type of metamaterial superstrate for dual-band directivity enhancement is presented as an alternative to a conventional FSS superstrate which is thicker. In the proposed new design, two strip-dipole arrays with the same periodicity, but with different alignments are placed above and below a thin dielectric layer to overcome the problem of different directivities realised at the two bands, when two FSS arrays with dissimilar periodicities are used. On the basis of unit-cell simulation, several important parameters that characterise the thin FSS superstrate are investigated, and the procedure for designing such a superstrate is described. Resonant frequencies and quality factors of the unit cell are compared with those of three FSS antenna composites with different quality factors and the optimal quality factors for the dual-band directivity enhancement are identified. Additionally, how to choose the optimal FSS array size for which the superstrate enhances directivity most efficiently is discussed. An antenna composite has been fabricated to validate the proposed approach, and the measured results show good agreement with the simulated ones.

A circuit which can function both as quadrature oscillator and as a universal biquad filter (low-pass, high-pass, band-pass, band-reject and all-pass functions) is introduced in this paper. Working as quadrature oscillator, the oscillation condition and oscillation frequency can be adjusted independently with the input bias currents. Functioning as a universal biquad filter, the quality factor and natural frequency can be tuned orthogonally via the input bias currents. The proposed circuit can work as either a quadrature oscillator or a universal biquad filter without changing circuit topology. The proposed circuit description is very simple, consisting of merely 2 current controlled current conveyor transconductance amplifiers (CCCCTAs) and 2 grounded capacitors. Without any external resistors and using only grounded elements, this circuit is thus suitable for IC architecture. The PSPICE simulation results are depicted, and the given results agree well with the theoretical anticipation. The maximum power consumption is approximately 3.78mW at ±1.5V power supplies.

This paper presents a quadrature voltage-controlled oscillator (QVCO) based on the coupling of two LC-tank VCOs. A simplified theoretical analysis for the oscillation frequency and phase noise displayed by the QVCO in the 1 3 region is developed, and good agreement is found between theory and simulation results. A prototype for the QVCO was implemented in a 0.35m CMOS process with three standard metal layers. The QVCO could be tuned between 1.64 and 1.97 GHz, and showed a phase noise of 140 dBc/Hz or less across the tuning range at a 3-MHz offset frequency from the carrier, for a current consumption of 25 mA from a 2-V power supply. The equivalent phase error between I and Q signals was at most 0.25 .

In this paper, the mechanism of plasma-charging damage (PCD) of metal-insulator-metal (MIM) capacitors as well as possible protection schemes are discussed. A range of test structures with different antennas simulating interconnect layout variations have been used to investigate the mechanism of PCD of MIM capacitors. Based on the experimental results, two models are presented, describing the relation between the damage and the ratio of the area of the exposed antennas connected to the MIM capacitors plates. New design rules are proposed in order to predict and automatically flag possible PCD sites. Furthermore, layout solutions to reduce PCD are suggested. Index Terms-Antenna ratio (AR), metal-insulator-metal (MIM), plasma-charging damage (PCD).

Achieving single-mode operation and highly directional (preferably unidirectional) in-plane light output from whispering-gallery (WG) mode semiconductor microdisk resonators without seriously degrading the mode Q-factor challenges designers of low-threshold microlasers. To address this problem, basic design rules to tune the spectral and emission characteristics of micro-scale optical cavity structures with nanoscale features by tailoring their geometry are formulated and discussed in this paper. The validity and usefulness of these rules is demonstrated by reviewing a number of previously studied cavity shapes with global and local deformations. The rules provide leads to novel improved WG-mode cavity designs, two of which are presented: a cross-shaped photonic molecule with introduced asymmetry and a photonic-crystal-assisted microdisk resonator. Both these designs yield degenerate mode splitting, as well as Qfactor enhancement and directional light output of one of the split modes.

This paper proposes a new method for verifying the design and characterization of radio frequency metal finger capacitors at low and high frequencies. Scalable models for metal finger capacitors for up to 20 GHz are produced using a simple and reliable modeling method. This work includes verification of the produced design and model using LC band pass filters. The metal finger capacitors and filters have been fabricated in Silterra's industry standard 180 nm 6 layer metal RF CMOS process.

This study presents new techniques for implementing continuous-time second-order band-pass filters with high-quality factors and asymmetric slopes. The techniques are centred around the realisation of two non-conventional transfer functions which include the non-integer-order Laplacian operator s a ; 0 , a , 1. Four main possible circuit realisations; one based on a frequencydependent negative resistor (FDNR), another based on an inductor and two based on multiple amplifier biquads (MABs) are given and verified using Spice and experimentally for both transfer functions. In addition, a field programmable analogue array (FPAA) realisation is tested and verified. Last but not least, a possible realisation using current conveyors is also given, tested and verified.

This article reports on the research to empirically determine which operations management problems are the most important to small service organizations. The authors asked managers of service organizations to rank a set of operations problems according to their relative importance using Q methodology. In this article, Q method is explained, signiÿcant factors are analyzed, and explanations are o ered for the ranking of the operations problems. The results indicate that forecasting, quality management, and resource utilization are important operational issues for service organizations. However, the results also indicate that facility location and layout, waiting line systems, and distribution requirements planning were for the most part unimportant to the respondent service organizations. In addition, Schmenner's service typology does not provide an explanatory basis for the variations in the factor results. Lastly, the results are used to suggest operations management techniques that should be taught to students who are expected to work in service organizations upon graduation.

A voltage-controlled oscillator (VCO) with a central frequency of 56 GHz and a 17% tuning range is presented. The oscillation frequency is tuned both by an analog input and by a 3-bit digital control bus using the same type of differential varactors. It achieves a record figure of merit, considering tuning range of 186.8 dBc/Hz and is able to address the full wireless high-definition multimedia interface band . The VCO is implemented in a 65-nm bulk CMOS process and dissipates 15 mW from a 1.2-V supply. Both fixed and parameterized electromagnetic models for inductors, interconnection structures, and transmission lines have been embedded in the classical design flow including layout verification and extraction, resulting in a very high level of simulation accuracy.

In this paper, impact of conventional silicon technology parameters on characteristics of passives is studied. For both inductors and capacitors, cost-effective modules, which integrate easily into wiring BEOL (Back-End Of Line) in a conventional silicon technology and provide high Q factor components are presented. For an inductor of 3 nH, designed for 2 GHz frequency applications, and fabricated in thick Cu as an add-on module, Q factor of ~24 is reached. The Metal Insulator Metal (MIM) capacitor module with outstanding RF performances and the Q factor ranging 100-1000 in the few GHz frequency range is developed in the Al BEOL. Compact lumped element SPICE models for both components are proposed and verified.

All-optical digital devices are key components for advanced signal processing in next generation optical networks and optical computing. In most digital systems, photonic integrated circuits are required to carry out high-speed energy efficient functionalities. In this paper, an entire set of integrable all-optical clocked flip-flops and an all-optical binary counter are proposed, as applications of SR latches and logic gates previously introduced in literature. The SR latch is based on gain quenching mechanism between two coupled ring lasers using a semiconductor optical amplifier (SOA) as active element. Photonic logic functions are carried out by exploiting four wave mixing (FWM) and cross gain modulation (XGM) nonlinear effects in SOAs. Different flip-flop logical functionalities, including SR-, D-, T-, and JK-types, as well as an all-optical binary counter, are obtained by adding one of the logic gates, or a combination of them, to the latch scheme. The effectiveness of the proposed schemes is demonstrated by extinction ratio and Q-factor measurements. All solutions are tunable in the whole C-band and can work at different counting rate without any reconfiguration. Photonic integration allows to increase the functioning rate beyond gigahertz and reduce the switching energy. Index Terms-Optical flip-flop, optical logic gates, optical signal processing, semiconductor optical amplifier (SOA). I. INTRODUCTION I N ORDER to meet the ever-increasing demand of data communication for future optical networks, high-speed digital processing is required.

This paper presents a multi-band CMOS VCO using a double-tuned, current-driven transformer load. The dual frequency range oscillator is based on enabling/disabling the driving current in the secondary port of the transformer. This approach eliminates the effect of switches connected directly to the VCO tank whose capacitance and on-resistance affect both the tuning range and the phase noise of a

A simple but efective technique has been applied to magnetically tune the quasi-TEoll mode dielectric resonators. The tuning was achieved by means of the fkrrite rod situated centrally in the dielectric resonator and extending over the shield The fkrrite parameters were changed by DC magnetic field. The method assures the high quality factor of the resonator, over 3.4% tuning range and suflcientb good spurious response. The tuning has been achieved by means of the ferrite rod situated centrally in the dielectric resonator and extending over the shield to the electromagnet system. The ferrite parameters were changed by DC magnetic field produced by the DC current. The method assures the high quality factor of the resonator, 3.4% tuning range and quite good spurious resppnse. Measured filter characteristics show low insertion loss 0.32 + 0.65 dB and excellent retum loss better than 30 dB at center frequency in the full tuning range.

A new MOS-C bandpass-low-pass filter using the current feedback operational amplifier (CFOA) is presented. The filter employs two CFOA's, eight MOS transistors operating in the nonsaturation region, and two grounded capacitors. The proposed MOS-C filter has the advantage of independent control of Q and ! o . PSpice simulation results for the proposed filter are given. Index Terms-Current feedback operational amplifiers, filters.

A micromechanical 13.1-MHz bulk acoustic mode silicon resonator having a high quality factor ( = 130 000) and high maximum drive level ( = 0.12 mW at the hysteresis limit) is demonstrated. The prototype resonator is fabricated of single-crystal silicon by reactive ion etching of a silicon-on-insulator wafer. A demonstration oscillator based on the new resonator shows single-sideband phase noise of 138 dBc/Hz at 1 kHz offset from the carrier.

A new transparent and robust watermarking method against JPEG compression attack based on a perceptual approach is proposed. The main idea is to embed the watermark into regions where the blocking artifact has no effect on the watermark. These regions are identified by using a spatial prediction model of blocking effect. A JND (Just-Noticeable-Difference) model is then used to control the embedding strength in order to ensure robustness and transparency of the watermarking. The performance of the proposed method is evaluated on a set of images and some common "signal processing" attacks.