Design of Compensated Coupled-Stripline 3-dB Directional Couplers, Phase Shifters, and Magic-T's—Part II: Broadband Coupled-Line Circuits

The problem of discontinuities in broadband multisection coupled-stripline 3-dB directional couplers, phase shifters, high-pass tapered-line 3-dB directional couplers, and magic-T's, regarding the connections of coupled and terminating signal lines, is comprehensively investigated in this paper for the first time. The equivalent circuit of these discontinuities proposed in Part I has been used for accurate modeling of the broadband multisection and ultra-broadband high-pass coupled-stripline circuits. It has been shown that parasitic reactances, which result from the connections of signal and coupled lines, severely deteriorate the return losses and the isolation of such circuits and also—in case of tapered-line directional couplers—the coupling responses. Moreover, it has been proven theoretically and experimentally that these discontinuity effects can be substantially reduced by introducing compensating shunt capacitances in a number of cross sections of coupled and signal lines. Results of measurements carried out for various designed and manufactured coupled-line circuits have been very promising and have proven the efficiency of the proposed broadband compensation technique. The theoretical and measured data are given for the following coupled-stripline circuits: a decade-bandwidth asymmetric three-section 3-dB directional coupler, a decade-bandwidth three-section phase-shifter compensator, and a high-pass asymmetric tapered-line 3-dB coupler.     

Field-extracted lumped-element models of coplanar striplinecircuits and discontinuities for accurate radiofrequency design andoptimization

Presents original lumped-element models of a large variety of coplanar stripline (CPS) circuits and discontinuities for accurate design and optimization of radiofrequency integrated circuits. These circuit models are extracted by applying a recently proposed deembedding technique called short-open calibration to calibrate the calculated field parameters obtained from the full-wave method of moments (MoM). It is realized by defining the two calibration standards, i.e., short and open elements, to evaluate and remove the error terms existing in the deterministic MoM algorithm, such as the approximation of port discontinuity and inconsistency of two-dimensional and three-dimensional characterizations of CPS external lines. In contrast to the static models, these field-extracted models can account for all the physical effects subject to the core area of CPS discontinuity, including frequency dispersion, high-order modes, and radiation loss. With this scheme, several CPS circuits and discontinuities are investigated over a wide frequency range to formulate their lumped-element models     

Noise reduction using compensation capacitance for bend discontinuities of differential transmission lines

Differential signaling has become a popular choice for multigigabit digital applications in favor of its low-noise generation and high common-mode noise immunity. Recalling from the full-wave solution of S-parameters, this paper presented a design methodology of analysis scheme to extract the equivalent circuits of discontinuities observed on the strongly coupled differential lines. Signal integrity effects of the bent differential transmission lines in a high-speed digital circuit were then simulated in the time domain. A dual back-to-back routing topology of bent differential lines to reduce the common-mode noise was further investigated. To alleviate the common-mode noise at the receiver, a novel compensation scheme in use of the shunt capacitance was also proposed. Furthermore, the comparison between the simulation and measured results validated the equivalent circuit model, coupled bends with compensation capacitance patch, and analysis approach.     

The Compensation of Step Discontinuities in TEM-Mode Transmission Lines

A method for the compensation of the effects due to discontinuities that arise when transmission lines of different characteristic impedance are joined is presented. The proposed method is not based calculating the equivalent circuit of the discontinuity but makes use of simple taper on the wider line at an impedance step to remove the effects of the discontinuity.     

射频连接器与微带线组件焊接过渡段阻抗补偿研究

射频连接器与微带线组件常用于通信系统电路中,而组件焊接过渡段的阻抗不连续会使电路中的信号损耗增大.针对该问题,本文对射频连接器与微带线组件焊接过渡段进行研究,基于传输线理论,建立焊接过渡段的等效电路模型.讨论了焊接过渡段特征阻抗不连续的原因,同时提出了补偿优化方案.此外,通过电磁场与电路的联合仿真,提取出补偿前后等效电路模型的电参数,从等效电路模型的角度分析了补偿方案对组件过渡段复杂电磁特性的影响.有限元仿真分析与实验测试结果显示,补偿后组件的性能显著提高,证明了补偿方案有效可行.     

Numerical TRL calibration technique for parameter extraction of planar integrated discontinuities in a deterministic MoM algorithm

In this letter, a thru-reflect-line (TRL) calibration procedure is applied and integrated with a full-wave method-of-moments (MoM) simulator for the parameter extraction of planar discontinuities and circuits. Three TRL calibration standards are numerically formulated and consistently characterized by the MoM simulator. An equivalent circuit model of a circuit discontinuity of interest can then be extracted by calibrating out the erroneous effect of port discontinuity in the deterministic MoM algorithm. As an example, a microstrip open-end circuit is comparatively studied in terms of its equivalent fringing capacitance, and effectiveness of the proposed technique is verified.     

Effets de propagation et de brouillage dans les interconnexions de circuits hybrides

The authors present results of modelling and time domain analysis for the interconnecting lines of hybrid circuits. The quasi tem approximation used in our analysis is justified by an electromagnetic study based on spectral domain method. So, we can use the transmission line concept for the time domain analysis. They present the theory of a simulator for the study of resistive coupled lines mounted in cascade. The effects of mismatching, point discontinuities and losses on signal distortions are discussed in the case of one transmission line. For a set of coupled lines, we clarify the parasiting effects between adjacent lines. We show that a screen-line can reduce these effects if some design rules are respected.     

Equivalent Transformations for Mixed-Lumped and Multiconductor Coupled Circuits

Distributed circuits consisting of a cascade connection of m -port stab circuits and multiconductor coupled transmission lines are equivalent to ones consisting of cascade connections of multiconductor coupled transmission lines whose characteristic impedances are different from original ones, m-port stub circuits, and an m-port ideal transformer bank. Because of the reciprocity of the circuit, values of transformer ratio must be identified. In the special case of a one conductor transmission line, these equivalent transformations are equivalent to Kuroda's identities. These extended equivalent transformations may be applied to mixed-lumped and multiconductor coupled circuits. By using these equivalent transformations, equivalent circuits and exact network functions of multiconductor nonuniform coupled transmission lines can be obtained.     

带状线低通滤波器的等效电路模型研究

所涉及的滤波器结构中包含开路端、T型接头等不连续性部分,因此在分析时应充分考虑到这些不连续部分所产生的传输损耗。基于传输线基本理论和矩量法(MoM),通过曲线拟合获得了偏心带状线开路端电容的解析公式,然后依据已有的微带线不连续性等效电路理论,提出了偏心带状线低通滤波器的等效电路模型。经实例验证发现,所得模型的计算结果与IE3D软件仿真结果吻合良好,而传输线理论法未考虑上述传输损耗,计算结果存在明显偏差。     

A generalized model for coupled lines and its applications totwo-layer planar circuits

A generalized network model for asymmetrical and inhomogeneous coupled lines has been derived based on normal mode parameters. This model is useful for synthesis of single and multilayer coupled-line circuits, such as planar baluns and directional couplers. The synthesis procedures are described and have been verified by comparing with analysis results     

A broadband and compact asymmetrical backward coupled-line coupler with high coupling level

A new wideband asymmetric microstrip coupled-line coupler with 3 dB coupling value and quadrature phase difference is presented. Compared with the conventional edge-coupled couplers, this structure, consisting of two different transmission lines (interdigital and conventional microstrip transmission lines) as coupled lines, achieves wider operating bandwidth and larger coupling level. The coupled-line length of the proposed structure is approximately λ_g/4. To characterize the structure, an equivalent circuit model has been established. A 3 dB designed and fabricated coupler with 0.2 mm spacing between coupled lines exhibits an amplitude balance of 2 dB from 2.2 GHz to 4.2 GHz. Good agreements between the full-wave simulation and equivalent circuit model results has been achieved and verified the effectiveness of the proposed circuit model. Also, measurement results have been presented.     

New Gate-Bias Voltage-Generating Technique With Threshold-Voltage Compensation for On-Glass Analog Circuits in LTPS Process

A new proposed gate-bias voltage-generating technique with threshold-voltage compensation for analog circuits in the low-temperature polycrystalline silicon (LTPS) thin-film transistors (TFTs) is proposed. The new proposed gate-bias voltage-generating circuit with threshold-voltage compensation has been successfully verified in an 8-mum LTPS process. The experimental results have shown that the impact of TFT threshold-voltage variation on the biasing circuit can be reduced from 30% to 5% under a biasing voltage of 3 V. The new proposed gate-bias voltage-generating technique with threshold-voltage compensation enables the analog circuits to be integrated and implemented by the LTPS process on glass substrate for an active matrix LCD panel.     

Transverse Resonance Analysis Discontinuities of Finline

A method of analysis is proposed for characterizing finline discontinuities. Two conducting or magnetic planes are inserted at some distances away from the discontinuity so as to obtain a closed resonant structure. A transverse resonance technique is then used to compute the resonant frequencies and, from these, the equivalent circuit parameters of the discontinuity. In the particular case when the discontinuity is removed, the method can be used to characterize uniform finlines.     

Asymmetric Coupled Transmission Lines in an Inhomogeneous Medium

Terminal characteristic parameters for a uniform coupled-line four-port for the general case of an asymmetric, inhomogeneous system are derived in this paper. The parameters (impedance, admittance, etc.) are derived in terms of two independent modes that propagate in two uniformly coupled propagating systems. The four-port parameters derived are of the same form as those obtained for the symmetric case resulting in similar port equivalent circuits for various circuit configurations considered by Zysman and Johnson. The results obtained should be quite useful in designing asymmetric coupled-line circuits in an inhomogeneous medium for various known applications.     

Propagation and circuit characteristics of inductively coupledsuperconducting microstrip

The propagation characteristics and circuit properties of two inductively coupled superconducting transmission lines are studied. An expression for the attenuation of the coupled-line modes is derived for the case of low loss. It is found that for transmission line geometries of practical interest the low-loss expression agrees well with the more general numerical solution. The numerical solution is used to determine the dispersion characteristics of inductively coupled lines as a function of the superconductor thickness and the operating temperature. An equivalent circuit, with the same dispersion equation, is presented along with the relationship between the circuit element values and the physical parameters of the line. The characteristic impedances of the two dominant coupled-line modes are derived from the equivalent circuit expressions     

Dielectric Waveguide Microwave Integrated Circuits---An Overview

An integrated circuit technique for microwave and millimeter wavelengths which uses refractive-type waveguides and signal processing coupled with planar integration techniques characteristic of microstrip microwave integrated circuits (MIC's) is described. Following a comparison of the optical and millimeter approaches to this circuit technique, a discussion of transmission lines and components for millimeter wavelengths is presented. System applications are also described.     

Design of a sensorless commutation IC for BLDC motors

This paper presents the design and realization of a sensorless commutation integrated circuit (IC) for brushless DC motors (BLDCMs) by using mixed-mode IC design methodology. The developed IC can generate accurate commutation signals for BLDCMs by using a modified back-EMF sensing scheme instead of using Hall-effect sensors. This IC can be also easily interfaced with a microcontroller or a digital signal processor (DSP) to complete the closed-loop control of a BLDCM. The developed sensorless commutation IC consists of an analog back-EMF processing circuit and a programmable digital commutation control circuit. Since the commutation control is very critical for BLDCM control, the proposed sensorless commutation IC provides a phase compensation circuit to compensate phase error due to low-pass filtering, noise, and nonideal effects of back-EMFs. By using mixed-mode IC design methodology, this IC solution requires less analog compensation circuits compared to other commercially available motor control ICs. Therefore, high maintainability and flexibility can be both achieved. The proposed sensorless commutation IC is integrated in a standard 0.35-/spl mu/m single-poly four-metal CMOS process, and the realization technique of this mixed-mode IC has been given. The proposed control scheme and developed realization techniques provide illustrative engineering procedures for the system-on-a-chip solution for advanced digital motor control. Simulation and experimental results have been carried out in verification of the proposed control scheme.     

Impact of NBTI on performance of domino logic circuits in nano-scale CMOS

Negative Bias Temperature Instability (NBTI) in pMOS transistors has become a major reliability concern in the state-of-the art digital circuit design. This paper discusses the effects of NBTI on 32 nm technology high fan-in dynamic OR gate, which is widely used in high-performance circuits. The delay degradation and power dissipation of domino logic, as well as the Unity Noise Gain (UNG), are analyzed in the presence of NBTI degradation. We have shown the degradation in the output inverter pMOS transistor of the domino gate has a dominant impact on the delay in comparison with the keeper impact. Based on this analysis we have proposed that upsizing just the output inverter pMOS transistor can compensate for the NBTI degradation. Moreover, the impact of tuning the duty cycle of the clock has been investigated. It has been shown that although the keeper and the precharge transistors experience more NBTI degradation by increasing the low level in the clock signal, the total performance of the circuit will improve. We have also proposed an adaptive compensation technique based on Forward Body Biasing (FBB), to recover the performance of the aged circuit.     

提高超声波测距精度方法的研究

在分析超声波测距系统回波信号处理存在问题的基础上,提出了两种提高测量精度的回波信号处理方法。采用时间增益补偿技术,补偿超声波在空气中的衰减,减少回波信号的起伏;由有源全波整流电路和微分电路等组成峰值时间检测电路,可正确检测回波的峰值到达时间。两种方法的采用,提高了超声波测距系统的测量精度。     

A novel method for modeling coupling between several microstriplines in MIC's and MMIC's

A technique for modeling the adjacent and nonadjacent couplings between several microstrip lines in microwave integrated circuits (MICs) and monolithic microwave integrated circuits (MMICs) is presented. The technique assumes that the primary transmission paths in the circuit can be modeled with conventional single or coupled microstrip models. A particular four-port model is then superimposed on the existing circuit for each adjacent or nonadjacent coupling that is present. This model uses analytical equations for microstrip coupled lines and is, therefore, fast and easy to compute