Derived Design Equations Research Articles

A Model for MOS Diodes With $V_{\rm th}$ Cancellation in RFID Rectifiers

A theoretical model for diode-connected MOS transistors with a threshold cancellation technique is developed. The model is based on a detailed analysis of the technique with internal threshold cancellation (ITC) and reveals design insight and performance limitations. Derived design equations illustrate the tradeoff between the voltage drop and the reverse leakage of the diode. Furthermore, a design procedure for the optimization of the power conversion efficiency (PCE) of a bridge rectifier with ITC MOS diodes was developed based on the model. A rectifier was designed and implemented in an austriamicrosystems 0.35-μm CMOS process, and Cadence simulation results of the PCE and the voltage conversion efficiency show good agreement with the model.

Development of strength prediction method of RC beams strengthened with prestressed CFRP plates by cross-section analysis

The purpose of this study is to evaluate the flexural behavior of Reinforced Concrete (RC) beams strengthened with prestressed Carbon Fiber Reinforced Polymers (CFRP) plates and to suggest the analytic equations of flexural capacity calculation for strengthening design. The evaluation of flexural behavior is carried out by parameter study experiments and the derived design equations are verified by the experimental results. The experimental parameters are concrete compressive strength, tensile reinforcement ratio, and prestressing level. Failure and fracture modes are observed and the efficiency of different CFRP prestressing level is studied. The results show that the non-prestressed specimens fail by spalling of the CFRP plate from the RC beam, while prestressed specimens fail due to CFRP plate failure. The presented equations of flexural capacity for RC beams strengthened with prestressed CFRP plates are shown to be sufficiently accurate in predicting flexural strengthening effectiveness of RC beams.

Compact Ultra-Wideband Low-Temperature Co-Fired Ceramic Bandstop Filter Using Semi-Lumped Resonators

A novel ultra-wideband bandstop filter with three semi-lumped resonators based on low-temperature co-fired ceramic technology is presented. Stopband rejection depth and bandwidth are controlled by the elements of each resonator. The filter not only has controllable transmission zeros, but it also features compact size due to the low-temperature co-fired ceramic 3-D structure and meandered topology. In addition, multi-layer capacitors are employed to enlarge the capacitance without size increments. A lossless transmission line model analysis is used to derive design equations. To validate the proposed structure, a multi-layer bandstop filter centered at 3.2 GHz with bandwidth of over 85% is designed and built. Good agreement between measured and simulated results is obtained.

Compact wideband bandstop filter using embedded capacitor

AbstractA new type of compact bandstop filter (BSF) using embedded capacitor in LTCC substrate is presented in this letter.Stopband rejection depth and bandwidth can be controlled simply by the value of the capacitor, while good return loss is realized by adjusting the impedance of two open‐circuited stubs. Further, filter size is miniaturized by the meandered closed‐loop structure. A lossless transmission line model analysis is used to derive design equations. To validate the proposed topology, a BSF centered at 4.5 GHz with bandwidth of 70% is designed and built. The implementation area is 0.35 λg × 0.25 λg, where λg is the guided wavelength at the mid‐stopband frequency. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1511–1514, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26848

Closed-Form Design Formulas for the Equivalent Circuit Characterization of Ferrite Inductors

Miniature inductors, consisting of thin-wire solenoidal or toroidal coils wound on a high-permeability soft ferrite core, find wide application in the filtering of noise or electromagnetic interference at RF. An understanding of the high-frequency parasitic and packaging effects of the inductor, such as stray capacitance, magnetic losses, self-resonance, etc., can be gained from an equivalent circuit characterization of the inductor. In this paper, we present a rigorous experimental method to fully characterize the RF behavior of ferrite inductors. The equivalent circuit parameters of the inductor, namely, series inductance, loss resistance, and stray capacitance, as well as the effective permeability of the core, are extracted in closed form from an accurate measurement of the RF impedance, without recourse to cumbersome optimization procedures usually followed in equivalent circuit extraction from measured data. We derive design equations for the equivalent circuit elements based on the proposed measurement-based model, and rigorously validate the model using inductors wound on commercial toroidal and rod-type Ni-Zn ferrite cores.

On the Noise Optimization of CMOS Common-Source Low-Noise Amplifiers

In this paper, we propose a general noise optimization technique for the CMOS common-source low-noise amplifiers. By directly employing the short-channel MOSFET - characteristic and van der Ziel's noise model, we derive design equations for the selection of the circuit design parameters, such as transistor sizes, passive component values, and bias voltages, which are subject to various gain and current consumption constraints. We also include several side effects, including the finite quality factor and the back-gate transconductance into the optimization process, and analyze their impact on the optimization results. Design examples that are based on a virtual but realistic process are given to verify our analysis and to give design intuition.

Sharp-Rejection Ultra-Wide Bandstop Filters

In this letter, a modified optimum bandstop filter (BSF) design is presented. Broad stopband and sharp rejection characteristics are achieved by realizing three transmission zeros near the passband edges. Stopband rejection depth and bandwidth can be controlled by the impedances of the configuration. A lossless transmission line model analysis is used to derive design equations. Further, a compact geometry is chosen by replacing the low impedance section with its equivalent dual-high impedance lines, which facilitates convenient folding. To validate the theoretical prediction, a single unit sharp-rejecting prototype BSF having a 20 dB rejection bandwidth of 126% at 1.5 GHz has been fabricated.

An X‐band 185° CMOS phase shifter MMIC for multiple‐antenna systems

AbstractThe design and implementation of an X‐band phase shifter MMIC using the standard 0.18‐μm CMOS process is presented. A transformed doublet varactor load is analyzed and applied to a 3‐dB quadrature coupler to exhibit large phase shift tuning range and low insertion loss with minimal variation. By using the derived design equations, the implemented CMOS reflection‐type phase shifter demonstrates a continuous phase shift tuning range greater than 185°, an average insertion loss of 5.2 dB with ±0.4 dB variation, and return losses better than 13 dB in 9–11 GHz. The total chip size including I/O pads is 0.76 × 0.79 mm2. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 645–648, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24131

Design of dual-band rat-race couplers

New designs of dual-band rat-race couplers are proposed. The desired dual-band operations are realised by adding tapped open stubs to the branches of the conventional rat-race coupler. It is found that these stubs can be implemented in two different ways to satisfy the conditions for dual-band applications, which results in two types of designs. The two different designs can be separately used to achieve low and high ratios between two operating bands, therefore providing enhanced design flexibility. The design formulas are developed using ABCD matrix and the even-odd mode analysis. On the basis of the derived design equations, a type I rat-race coupler working at 1 GHz/3.5 GHz and a type II coupler working at 2 GHz/5 GHz are devised and fabricated on Rogers's RO3006 printed circuit boards. Measurement results prove the design concepts.

A novel formulation of the dynamic balancing of five-bar linkages with applications to link optimization

In this report, we derive design equations and techniques for the dynamic balancing of five-bar linkage, using a novel and simplified approach. Firstly, in order to derive the dynamic equations of the mechanism we have applied the natural orthogonal complement method. Subsequently, an optimization method for the dynamic balancing of the linkage is proposed. The conditions of dynamic balancing of the five-bar linkage are expressed as seven equations and four inequalities, with twelve linkage parameters. The dynamic balancing of the mechanism is formulated and solved as an optimization problem under equality constraints. The application of the new approach is illustrated through a numerical example.

Suggestion of flexural capacity evaluation and prediction of prestressed CFRP strengthened design

The purpose of this study is to evaluate the flexural behavior of RC (Reinforced Concrete) beams strengthened with prestressed CFRP (Carbon Fiber Reinforced Polymers) plates, and to suggest the analytic equations of flexural capacity calculation for strengthening design. The evaluation of flexural behavior is carried out by parameter study experiments, and the derived design equations are verified by the experimental results. The experimental parameters are concrete compressive strength, tensile reinforcement ratio, and prestressing level. Failure and fracture modes are observed and the efficiency of different CFRP prestressing levels is studied. The results show that the non-prestressed specimens fail by spalling of the CFRP plate from the RC beam, while prestressed specimens fail due to CFRP plate failure. The presented equations of flexural capacity for RC beams strengthened with prestressed CFRP plates are shown to be sufficiently accurate in predicting flexural strengthening effectiveness of RC beams.

임의의 종단 임피던스를 갖는 DC Block의 완전 정합

Design equations of DC blocks terminated in arbitrary impedances are newly suggested and a microstrip DC block is tested for the perfect matching. The DC block is a two-port passive component and the power excited at a port is transmitted into another port. However, all the excited power at the input can not be delivered to the output and therefore most of the conventional DC blocks can not be perfectly matched with arbitrary termination impedances. To solve the matching problem, its one-port equivalent resonant circuit model, from which design equations can be derived, is newly suggested. Using the derived design equations, any DC block can be designed, perfectly matched without any restriction of coupling coefficients. To verify the derived design equations, measurements were carried out and the results are in good agreement with prediction, showing insertion and return losses at 4.1 ㎓ are 0.82 ㏈ and －31 ㏈, respectively.

Confining Reinforcement for High-Strength Concrete Columns

This paper describes a comprehensive parametric study of reinforced high-strength concrete (HSC) columns undertaken to verify the current ACI 318 and NZS 3101 code provisions of confining reinforcement in the potential plastic hinge regions of HSC columns. A full range of parameters having significant influences on the available strength and curvature ductility factor in the potential plastic hinges of the columns during cyclic flexure are examined. Previously derived stress-strain relationships for compressed HSC confined by various quantities, yield strengths, and arrangements of transverse reinforcement are used in cyclic moment-curvature analyses of a range of reinforced HSC columns to derive design equations. The proposed design equations are able to determine the quantities of transverse reinforcement required for the specified curvature ductility demands of HSC columns. Accuracy of the proposed design equations was checked by comparing with experimental data reported in prior literature, and a satisfactory correlation was found.

General design equations, small-sized impedance transformers, and their application to small-sized three-port 3-dB power dividers

In this paper, design equations for three-port power dividers have been derived. These design equations are available for both arbitrary power divisions and arbitrary termination impedances, and many sets of design equations are possible. Therefore, the design equations may be called general design equations and an arbitrary design impedance A is introduced to describe them. On the basis of the derived general design equations, a coplanar three-port power divider with a power split ratio (3 dB) terminated by 50, 60, and 70 /spl Omega/ is designed with A=33.33 /spl Omega/, so that a commercially available resistor 100 /spl Omega/ can be used for the isolation resistance. Additionally, to reduce the size of transmission-line impedance transformers, two types of small-sized impedance transformers are designed, named a constant VSWR-type transmission-line impedance transformer (CVT) and a constant conductance-type transmission-line impedance transformer (CCT) and compared with conventional reduced-sized impedance transformers. These impedance transformers are designed in the low-Q region on the Smith chart. Therefore, they show wide-band properties. To make sure that the derived design equations of CVTs and CCTs are reasonable, four 1;6:1 impedance transformers, CVT 20/spl deg/, CVT 30/spl deg/, CCT 15/spl deg/, and CCT 20/spl deg/ have been fabricated in microstrip technology and measured. The measured results show the expected tendency. Based on the CVTs and CCTs, small-sized three-port 3-dB power dividers are constructed and named a constant VSWR-type three-port 3-dB power divider (CVT3PD) and a constant conductance-type three-port 3-dB power divider (CCT3PD). For the CVT3PD and CCT3PD, perfect isolation conditions are derived, and it is shown that the perfect isolation circuit (I.C) must be composed of resistance combined with capacitance or inductance in the case that the length of transmission lines is not /spl lambda//4. These I.Cs are quite different from conventional ones composed of only resistance. Finally, on the basis of the derived perfect isolation impedance, CVT3PD and CCT3PD are designed and simulated, giving the possibility that a CCT3PD can be realized with the electrical length 15.30/spl deg/ of the transmission lines.

Asymmetric four-port and branch-line hybrids

Two different asymmetric branch-line hybrids, a conventional-direction asymmetric branch-line hybrid (CABH) and an anti-conventional-direction asymmetric branch-line hybrid (AABH) are discussed and their design equations are derived. On the basis of the derived design equations, a uniplanar CABH was fabricated with coplanar waveguide (CPW) technology and measured.

Standing wave analysis of SMB chromatography: Linear systems

AbstractThe concept of standing concentration waves is introduced to derive design equations for continuous moving bed (CMB) processes. For linear isotherm systems, simple equations are derived from the analysis to link product purity and recovery to zone lengths, bed movement velocity, flow rates, column capacity factors, and mass‐transfer coefficients. Once product purity, recovery and feed flow rate are specified for a given system, the zone flow rates and bed movement velocity that provide the highest throughput and the lowest solvent consumption can be determined from the solutions. In a given system, there is a trade‐off between product purity and throughput. If bed volume and product purities are fixed, the longer the zone lengths, the higher the throughput. Simulations based on a linear driving force model that considers axial dispersion and lumped film and intraparticle diffusion are used to compare the column profiles and effluent histories of CMB and simulated moving bed (SMB). A numerical algorithm is introduced to allow simulation of both CMB and SMB operations using the same program. The comparison shows that the design equations derived for CMB systems are applicable to SMB systems. Finally, the standing wave solutions are used to analyze an experimental SMB system from the literature (Ching et al., 1991). Simulations agree closely with the data and the predictions of the theoretical analysis.

Design of VCSEL's for feedback insensitive data transmission and external cavity active mode-locking

We present a detailed study of feedback effects in the regime of -60 to -2 dB feedback of top surface-emitting vertical-cavity laser diodes (VCSEL). Feedback dependent properties such as threshold current reduction, mode-locking, relative intensity noise and power penalty in high data rate transmission are shown to be strongly dependent on the output mirror reflectivity. A two-resonator model is applied to derive design equations and to explain feedback properties. In 1 Gbit/s single-mode fiber transmission VCSEL's with top Bragg mirror reflectivity of 99.8% require a power penalty of 1.5 dB at -10 dB feedback level while similar VCSEL's with 99.0% top mirror reflectivity run into a noise floor of 10/sup -4/ bit-error rate for the same feedback conditions. Strong feedback is used to generate nearly transform limited mode-locked 22 ps pulses with timing jitter below 1 ps in a single-mode fiber VCSEL module of 1.7-mA threshold current.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Polar coordinate quantizers that minimize mean-squared error

A quantizer for complex data is defined by a partition of the complex plane and a representation point associated with each cell of the partition. A polar coordinate quantizer independently quantizes the magnitude and phase angle of complex data. The authors derive design equations for minimum mean-squared error polar coordinate quantizers and report some interesting theoretical results on their performance, including performance limits for " phase-only" representations. The results provide a concrete example of a biased estimator whose mean-squared error is smaller than that of any unbiased estimator. Quantizer design examples show the relative importance of magnitude and phase encoding.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Design of Sheet Dies for Minimum Residence Time Distribution: A Review

Abstract The various die designs that have been proposed for the manufacture of sheets and flat films from polymeric materials are reviewed, along with the corresponding flow analysis and derived design equations. Successively, the T-die, the linearly tapered coat-hanger die, the curvilinearly tapered coat-hanger die (with manifold of circular or rectangular cross-section), and the fishtail die are examined. In each case, care is taken to outline the assumptions used to derive the equations, and to state the advantages and disadvantages of each design. The limits of these mentioned assumptions are explained and illustrated. Particular attention is paid to the aspects of the design which affect the processing of sensitive or reactive materials (i.e., residence time distribution and wall shear stress).

An approximate model for binary azeotropic distillation design

A simple analytical model has been developed for representing vapor-liquid equilibrium data in binary azeotropic mixtures. The method treats the azeotrope as a new pure component and considers the mixture to be composed of two independent binary subsystems; component 1 + azeotrope and azeotrope + component 2. After suitable variable transformations, each subsystem can then be represented by a constant relative volatility type model. The resulting vapor-liquid equilibrium models have been used to derive design equations for binary azeotropic distillation columns.