Narrow-band microwave filter design

In this article, Dishal's concepts, EM simulation, and the port-tuning concept are combined as a powerful procedure for narrow-band filter design. When applied to an EM-based filter prototype, port tuning gives a direct indication of the magnitude and direction of the tunings needed to correct coupling errors and resonator frequency errors. An EM-based filter prototype potentially captures all the physics of the real hardware and includes second-order effects that may be impossible to describe using analytical models. After iteratively reducing all the errors in the EM-based prototype, the first hardware prototype that was built will meet performance goals. This design methodology can be applied to simple all-pole Chebyshev filters and to more complex cross-coupled filters that place transmission zeros in the stopbands.     

Synthesizing microwave resonator filters

In this article, analytic and optimization-based methods for the synthesis of dual-passband microwave filters are presented. First, the frequency transformations for synthesizing dual-passband filters is described. For the filters in which the reflection and transmission zeros cannot be found analytically using frequency transformations, an optimization (or trial-and-error) procedure for a systematic approach is described. The reflection and transmission zeros obtained by the frequency transformation were found to be good initial values for the optimization process.     

Real-time assessment of a symmetrical component and microcontroller based distance relay

This paper presents the design, implementation and real-time assessment of a microcontroller based digital distance relay that can be used for the protection of power transmission lines. The proposed design is implemented using a general-purpose Intel 8097 microcontroller and custom-made filters, operational amplifiers, sample-and-hold amplifiers, multiplexers, and analog-to-digital converters. The relay software is based on a computationally efficient symmetrical component based fault distance estimation algorithm. Results of the performance assessment studies on this algorithm have shown promising fault distance estimates for first-zone faults on the protected transmission line. Real-time implementation of the symmetrical component based fault distance estimation algorithm is presented and discussed in this paper. Hardware and software tools were used to design and fabricate a microcontroller based distance relay using the above-mentioned algorithm. This paper describes details of the design of the distance relay. A test setup in the laboratory using a transmission line model was used to generate data to assess the real-time response of the designed relay. High-speed relay operation of the order of one cycle is demonstrated in the test results.     

Design and simulation of modular 2n to 1 quantum‐dot cellular automata (QCA) multiplexers

In this paper a novel design of a quantum‐dot cellular automata (QCA) 2 to 1 multiplexer is presented. The QCA circuit is simulated and its operation is analyzed. A modular design and simulation methodology is developed, which can be used to design 2ⁿ to 1 QCA multiplexers using the 2 to 1 QCA multiplexer as a building block. The design methodology is formulated in order to increase the circuit stability. Copyright © 2009 John Wiley & Sons, Ltd.     

Explicit design formulas for current‐mode leap‐frog OTA‐C filters and 300 MHz CMOS seventh‐order linear phase filter

The leap‐frog (LF) configuration is an important structure in analogue filter design. Voltage‐mode LF OTA‐C filters have recently been studied in the literature; however, general explicit formulas do not exist for current‐mode LF OTA‐C filters and there is also need for current‐mode LF‐based OTA‐C structures for realization of arbitrary transmission zeros. Three current‐mode OTA‐C structures are presented, including the basic LF structure and LF filters with an input distributor or an output summer. They can realize all‐pole characteristics and functions with arbitrary transmission zeros. Explicit design formulas are derived directly from these structures for the synthesis of, respectively, all‐pole and arbitrary zero filter characteristics of up to the sixth order. The filter structures are regular and the design formulas are straightforward to use. As an illustrative example, a 300 MHz seventh‐order linear phase low‐pass filter with zeros is presented. The filter is implemented using a fully differential linear operational transconductance amplifier (OTA) based on a source degeneration topology. Simulations in a standard TSMC 0.18µm CMOS process with 2.5 V power supply have shown that the cutoff frequency of the filter ranges from 260 to 320 MHz, group delay ripple is about 4.5% over the whole tuning range, noise of the filter is 420nA/√Hz, dynamic range is 66 dB and power consumption is 200 mW. Copyright © 2008 John Wiley & Sons, Ltd.     

Ladder tuning‐block partitioned filters for simplified tuning

In this paper, we present a procedure for the design of low‐sensitivity, active‐RC filters that permits efficient functional tuning during the manufacturing process. Filters with finite zeros, such as elliptic (Chebyshev–Cauer) low‐pass filters are primarily considered, although the method can be applied to the design of other filters, e.g. allpole filters, as well. We show how to partition a given ladder filter into two parts. The first is a ladder filter of reduced order compared to the original; the second is a second‐ or third‐order active‐RC filter section, the ‘tuning block’, which, alone is used to tune the overall filter. The ladder, the components of which are fixed, provides most of the selectivity, while the cascaded tuning block determines the band‐edge characteristics and can be tuned relatively easily. A detailed design procedure for the filter partitioning is given. By obtaining a doubly terminated ladder filter, which is cascaded with a tuning block, both the inherent low sensitivity of the ladder and the tunability of the tuning block, are maintained. A Monte Carlo analysis of the partitioned filter demonstrates that the low sensitivity with respect to component tolerances, achievable by maintaining a doubly terminated ladder structure for the larger partitioned part of the filter, is preserved. Copyright © 2012 John Wiley & Sons, Ltd.     

Optimal design of third‐order microstrip bandpass filters by direct synthesis technique (DST)

To design microstrip filters is not easy for the sake of their distributed‐element effect. Undoubtedly, to understand their physical mechanism is very important to their design. In this paper, one effective approach to design some third‐order microstrip bandpass filters with each of 2 transmission zeros at each side of the passband is discussed. Lumped‐element equivalent circuits are used to represent these microstrip filters. Then, these lumped‐element equivalent circuits can be synthesized by direct synthesis technique we recently proposed, so that it is likely to calculate initial structural parameters of these microstrip filters and then facilitate their design. Verified by the measured results of the filter designed through the approach in this paper, the performance of the filters is close to ideal frequency responses. Furthermore, another third‐order microstrip bandpass filter is presented, in which open‐circuited stubs at input/output ports are introduced to suppress one specified harmonic to improve out‐of‐band attenuation.     

Design of selective lowpass sampled-data and digital filters exhibiting equiripple amplitude and phase error characteristics

A method is presented for the design of reciprocal reactant sampled-data and digital filters exhibiting equiripple passband and stopband amplitude characteristics and approximating a linear phase characteristic such that the phase error response is equiripple too. the passband amplitude characteristic approximates unity transmission and the stopband amplitude characteristic approximates zero. Odd- and even-degree cases are considered separately. the stopband amplitude response is controlled by an arbitrary number of finite transmission zeros together with two (one) zeros at infinity for even (odd) transfer functions. All the available degrees of freedom are used for controlling the filter performances. Thus the resulting solutions are selective and have good amplitude and phase characteristics. A comparison between our method and a recently published method shows that this approach has higher stopband loss and smaller phase error ripple with wider bandwidth.     

A novel QCA implementation of MUX-based universal shift register

QCA (Quantum-dot Cellular Automata) is an alternative technology for CMOS that has a low power consumption and high density. QCA extensively supports the new plans in the field of nanotechnology. Applications of QCA technology as an alternative method for CMOS technology in nano-scale have a hopeful future. This paper presents the successful design, implementation and simulation of 2 to 1, 4 to 1 and 8 to 1 multiplexer with the minimum area as compared to the previous models in QCA technology. In this paper, by means of 4 to 1 multiplexers including D-Flip Flop (D-FF) structure in QCA, we present an 8-bit universal shift register. The structure of the 8-bit universal register is extendable to 16-bit, 32-bit and etc. In this paper, the successful simulation of 2 to 1, 4 to 1 and 8 to 1 multiplexers, including D-FF and finally 8-bit universal register structure in QCADesigner is provided. The multiplexers and D-FF presented in this paper have the minimum complexity, area and delay compared to the previous models. In this paper, the implementation of 8-bit universal shift register, by means of 4 to 1 multiplexers and D-FF are presented in QCA technique which have the minimum complexity and delay. In the proposed design of the 8-bit universal shift register, the faults are likely to occur at 2 to 1 multiplexers and D-FF. In this article, 2 to 1 multiplexers and D-FF are investigated from the cell missing and possible defects. Considering the pipeline being the virtue of QCA, the 8-bit universal shift register has a high speed function. This 8-bit universal shift register may be used in the high speed processors as well as cryptography circuits.     

Multiloop feedback unsymmetrical active filters using quads

In this paper, a general design procedure for high order unsymmetrical active filters is presented using a special configuration of quads. Quads are 4th order subsection blocks using biquads in a special manner. It is shown that the determination of network parameters is not dependent on frequency range, and that the design procedure is simpler than other multiloop feedback (MF) topologies. The transmission zeros of the transfer function are derived directly from the zeros of the biquadratic blocks and thus feedforward or summation techniques are not required.     

Poles and zeros of bandpass filters for high-performance sigma-delta modulators

High-performance bandpass sigma-delta modulators find applications in digital mobile radio for accurate analogue-to-digital conversion in receivers. An approach based on the positioning of the poles and zeros is proposed for the digital design of the high-order loop filters which are required. Inverse notch filter sections are cascaded in a first step and then poles and zeros are moved to meet the performance objectives and achieve system stability. A distinct feature of the analysis and design technique presented is that it takes stability into account explicitly. Examples illustrate the practicality of the method as well as the level of performance which can be achieved in theory. the integrated circuit realization still has to be investigated to confirm the potential of the proposed design approach.     

Diffraction-grating-based (de)multiplexer using image plane transformations

We present the concept of using image plane transformations with free-space diffraction-grating-based multiplexers. We demonstrate two examples of a diffraction-grating-based multiplexer that take advantage of image plane spatial transformations. We show that the use of such spatial transformations has unique advantages for multiplexing schemes. We also demonstrate unique system applications enabled by these multiplexers.     

高压直流输电系统直流滤波器的设计

直流滤波器是抑制高压直流输电(HVDC)直流侧谐波的最有效、最典型且应用最广泛的设施,其设计的优劣既牵涉到HVDC系统的运行性能和安全稳定性,又关系到整个系统总投资的高低。为深入研究直流滤波器的设计,首先总结了现有HVDC工程直流滤波器的配置现状,在分析直流滤波器电路结构和阻抗-频率特性的基础上,忽略电阻的影响,根据调谐点滤波器阻抗Z=0,推导了双调谐滤波器和三调谐滤波器设计的精确公式,提出了详细的参数设计方法,而公式有多组解,选取最大的串联谐振频率rω1那一组解,此时滤波器阻抗-频率特性在谐振点附近的曲线比较平坦,滤波效果最好。然后以HVDC实际工程直流滤波器参数进行验证,结果表明所提出的公式完全正确,可为直流滤波器的参数设计提供工程指导。最后以满足等效干扰电流为基本要求,对某HVDC工程的直流滤波器进行了实例设计。     

An accurate digital low-pass filter for transmission line protection

The paper presents a procedure for designing, testing and evaluating digital low-pass filters for the removal of high-frequency transients from transmission line short-circuit voltage and current waveforms, as is required for certain digital distance relays and may be useful in other similar applications. The procedure is based on the ‘trapezoidal’ type of low-pass digital filter which has characteristics that enable low-order digital filters to be achieved. Criteria for the design and optimization of such filters in the foregoing type of application are also presented.     

Synthesis of symmetrical dual mode in-line prototype networks

An analytic synthesis technique is developed for symmetrical dual mode in-line prototype networks up to and including degree 12 networks. Due to the symmetrical realization, the even mode coupling matrix completely defines the network and one particular form representing the double cross-coupled array, may be obtained directly from the transfer function. Commencing with this matrix, rotational transformation are used to transform the even mode matrix into the form required for a dual mode in line structure. Analytical solutions are obtained for degrees up to and including 12 and the necessary realizability conditions are determined for each case. Explicit formulas for the angles of rotation are given and for degrees up to and including 10, a complete set of explicit formulas are provided for the final coupling matrix. To assist in the design of the in-line structure, tables of element values for filters having 20 dB and 26 dB return loss and possessing the minimum number of transmission zeros at infinity are tabulated.     

Compact third-order microstrip bandpass filter designed by the distributed- to lumped-element equivalence

In reality, it is not easy to design microstrip filters for the sake of distributed-element effect. It is an effective approach to approximate distributed-element structures through appropriate lumped-element circuits. In this paper, some basic microstrip structures are discussed, whose equivalent lumped-element circuits are derived. Then, a novel microstrip filter is obtained by connecting these microstrip structures, according to the similar topology of the third-order lumped-element bandpass filter. The equivalent lumped-element counterpart of the proposed microstrip filter clearly reveals its physical mechanism, ie, how the resonances are created and coupled and how the transmission zeros are created. Furthermore, a set of the design formulas are presented, which can be used to calculate initial structure parameters and then facilitate design process. The proposed microstrip bandpass filter can realize a third-order elliptic bandpass response with one transmission zero at each side of the passband. In addition, two short-circuited stubs are added to input/output ports to create the third transmission zero. The filter is featured by good frequency selectivity and out-of-band suppression. For demonstration, an actual example was designed, fabricated, and measured.     

电力线传输特性和噪声干扰对通信性能的相对影响

电力线载波通信技术是支撑智能电网信息传输的重要技术之一,但是电力线作为信息传输通道时具有复杂的传输特性和较多的噪声干扰。为分析电力线信道的频率选择性对通信性能的影响及其和信道噪声的相对作用,设计滤波器模拟具有不同频率选择性的电力线信道,用米德尔顿A类噪声模拟信道中不同强度的噪声,采用基于OFDM技术的G3-PLC标准建立窄带电力线载波通信系统模型进行仿真分析。结果表明：电力线载波通信中,低速率传输数据或信号带宽较小时噪声干扰比频率选择性对系统性能影响大。随着数据传输速率或信号带宽增加,信道的频率选择性对系统性能的影响逐步增大。该结论为设计和研究电力线载波通信系统提供了理论分析基础。     

Iterative design of two-channel IIR perfect construction QMG filters

A simple rapidly convergent method is described for the design of two-channel IIR perfect reconstruction quadrature mirror filters. For any prescribed characteristic, it has been shown how one can construct a stable two-channel IIR banks, starting from any random transmission zero locations. A simple rapidly convergent search algorithm is also described for the determination of the exact locations of these transmission zeros, such that the filter has equiripple pass and stop responses as well as almost constant group delay. Illustrative examples are also given to show that the proposed design method competes very well with the existing design methods. © 1998 John Wiley & Sons, Ltd.     

Design of efficient QCA multiplexers

A new methodology to realize efficient multiplexers using quantum‐dot cellular automata (QCA) is presented in this paper. The novel designs here demonstrated fully exploit the intrinsic logic capabilities of the basic building block in the QCA domain: the Majority Gate. An efficient logic formulation is derived for the 4:1 multiplexing function that can be recursively applied to the realization of multiplexers with any fan‐in, by adding in the worst‐case path only one level of Majority Gate for each input doubling. A 16:1 multiplexer designed by applying the proposed recursive approach requires less than 1600 cells and consumes only 12 clock phases to complete the operation. Copyright © 2015 John Wiley & Sons, Ltd.     

A silicon MEMS optical switch attenuator and its use in lightwavesubsystems

A single-mode fiber connectorized microelectromechanical systems (MEMS) reflective optical switch attenuator operating in the 1550-nm wavelength region is described. The device consists of an electrostatically actuated gold-coated silicon vane interposed in a fiber gap yielding 0.81-dB minimum insertion loss in the transmit state and high transmission isolation in the reflection state with 2.15-dB minimum return loss. The switch attenuators also work as continuously variable optical attenuators capable of greater than 50-dB dynamic range and can be accurately regulated with a simple feedback control circuit. Switching voltages were in the range of 5-40 V and a switching time of 64 μs was achieved. The MEMS switch can be used in optical subsystems within a wavelength-division-multiplexed (WDM) optical network such as optical power regulators, crossconnects, and add/drop multiplexers. We used a discrete array of 16 switch attenuators to implement a reconfigurable 16-channel 100-GHz spacing WDM drop module of an add/drop multiplexer. Thru-channel extinction was greater than 40 dB and average insertion loss was 21 dB. Both drop-and-transmit of multiple channels (11-18-dB contrast, 14-19-dB insertion loss) and drop-and-detect of single channels (>20-dB adjacent channel rejection, 10-14-dB insertion loss) were demonstrated