Design of robust nearfield wideband beamformers with optimum subband constraints

Design of nearfield wideband beamformers robust against microphone mismatches is of great interest in practical applications. The state-of-the-art design approach is based on the fullband processing. In this paper, the over-constraint problem suffered by the fullband design approach is studied, which typically leads to the undesired signal distortion with low-pass filtered characteristics. To combat the over-constraint problem, a new design approach for robust nearfield wideband beamformers with optimum subband constraints is proposed. The performance of the proposed design approach is evaluated and compared with the fullband design counterpart via design examples.     

Integrated Approach to Microwave Design

A new, integrated approach to microwave design is presented involving concepts such as optimal design centering, optimal design tolerancing, optimal design tuning, parasitic effects, uncertainties in models and reference planes, and mismatched terminations. The approach is of the worst case type, and previously published design schemes fall out as particular cases of the ideas presented. The mathematical and computational complexity as well as the benefits realized by our approach is illustrated by transformer examples, including a realistic stripline circuit.     

Selection of optimal closed-loop controllers for DC-DC voltage regulators based on nominal and tolerance design

This paper discusses a tolerance design approach for the feedback compensation networks of DC/DC switching regulators, identifying the most reliable solutions among different feasible alternatives that fulfil closed-loop design constraints. A voltage-mode-regulated DC/DC buck converter is considered as a case study. Given the performance and stability constraints, as tolerance ranges for crossover frequency and phase margin, feasible design solutions are sought by means of Monte Carlo and interval arithmetic computations. The search space is a set of available commercial values of RC parameters and related tolerances. Best design is identified by a weighted fitness function, exploring the set of solutions provided by different design approaches. The results presented in the paper highlight that the tolerance design approach allows one to find compensation networks that fit the given performance/robustness priorities better than those ones found by means of the classical nominal design approach.     

ARIADNE: A constraint-based approach to computer-aided synthesis and modeling of Analog integrated circuits

The ARIADNE approach to computer-aided synthesis and modeling of analog circuits is presented. It is a mathematical approach based on the use of equations. Equations are regarded as constraints on a circuit's design space and analog circuit design is modeled as a constraint satisfaction problem. To generate and efficiently satisfy constraints, advanced computational techniques such as constraint propagation, interval propagation, symbolic simulation, and qualitative simulation are applied. These techniques cover design problems such as topology construction, modeling, nominal analysis, tolerance analysis, sizing and optimization of analog circuits. The advantage of this approach is the clear separation of design knowledge from design procedures. Design knowledge is modeled in declarative equation-based models (DEBMs). Design procedures are implemented into general applicable CAD tools. The ARIADNE approach closely matches the reasoning style applied by experienced designers. The integration of synthesis and modeling into one frame and the clear separation of design knowledge from design procedures eases the process of extending the synthesis system with new circuit topologies, turning it into an open design system. This system can be used by both inexperienced and experienced designers in either interactive or automated mode.     

Composite Coupler Design

Unequal power splitters and combiners are generally limited by the line widths which can be practically synthesized in a given transmission medium. This practical limitation on the ratio of unequal power division can be extended by incorporating the same types of couplers into a composite design. The general composite design approach outlined in this paper rises three couplers (three terminal couplers) to generate a new three-terminal circuit. The design equations are derived for the composite approach and summarized in graphic form. The feasibility of the composite design approach is demonstrated by the construction of a 5.76-dB differential coupler rising intenally series-terminated Wilkinson couplers. The circuit was designed, analyzed via computer, and finally built and tested. The results from the composite design are compared to that of a single Wilkinson coupler design.     

A mechatronic approach to microsystem design

This paper discusses the implementation of a concurrent-engineering view of microsystem design. The proposed concurrent-engineering or mechatronic approach to the design of hybrid microsystems is illustrated by three case studies. First, the design of an advanced computer writing tool is discussed. The design of this consumer product requires a mechatronic approach at different functional levels and at different levels of miniaturization. Another illustration of this approach is the design of an implantable drug delivery device. A device for solid drug delivery, as well as a device for liquid drug delivery, are presented. It is demonstrated that miniaturization can be obtained by a combination of functions in a single component. The multiplication of functions in a single component automatically leads to a concurrent-engineering approach far the design. Finally, the micromanufacturing of silicon parts by electrodischarge machining is described. It is demonstrated that electrodischarge machining of silicon is not only feasible, but forms an interesting and complementary technology to traditional silicon micromachining. Therefore, this powerful manufacturing technique opens the way for concurrent engineering of real three-dimensional micromechanical sensors and actuators with integrated processing electronics on the same wafer     

A Direct Synthesis Approach for Microwave Filters With a Complex Load and Its Application to Direct Diplexer Design

This paper presents a direct synthesis approach for general Chebyshev filters terminated with a complex load. The new approach is based on the fact that the polynomial functions for synthesizing the filters are composed for any matched loads. By normalizing the polynomial functions with assumed complex matched load impedance by a real reference load impedance using power waves normalization, a set of new polynomial functions for the same filter, but with real load impedance, can be formulated, from which the coupling matrix for the physical filter design can be obtained using a standard direct filter synthesis approach. This new direct synthesis approach can find many applications. A practical application is the direct diplexer design with a realistic junction model being taken into account. With the diplexer design is concerned, a fast-converged iterative scheme is proposed. The effectiveness and the validation of the proposed scheme are demonstrated by two design examples     

一种基于SNMP TRAP的告警确认机制

首先介绍了Manager—Agent管理模型、SNMP协议的基本知识以及TRAP操作的基本机制，然后针对TRAP机制中存在的无响应问题以及其在通讯设备应用中引发的漏告警和假告警现象，提出了一种增强型告警确认机制，并且从该机制的功能设计、数据设计和流程设计3个方面进行了详细阐述，最终通过采用告警一恢复确认重发机制和告警刷新机制相结合的方法解决了上述问题。需要指出该方法虽然采用了SNMP协议定义的标准操作来达到目的，但是其实现机制是不符合SNMP规范的，如果采用该套机制需要SNMP Manager和Agent进行配合设计开发。     

运用CAD技术进行光电器件版图设计

着眼于设计器件的要求，从ＣＡＤ技术的开发环境入手，采用全定制的设计方法和分层设计的概念，较方便地达到了光电器件版图设计的基本要求。     

A clock-free chip set for high-sampling rate adaptive filters

As digital signal processing systems become larger and clock rates increase, the typical design approach using global clock synchronization will become increasingly difficult. The application of asynchronous clock-free designs to high-performance digital signal processing systems is one promising approach to alleviating this problem. To demonstrate this approach for a typical signal processing task, the system architecture and circuit design of a chip set for implementing high-rate adaptive lattice filters using the asynchronous design techniques is presented.This research was sponsored in part by the Semiconductor Research Corporation and by DARPA.     

一种基于主体的可信网构软件设计方法

 本文提出了一种基于主体的网构软件设计方法ABDPI,该方法对传统的多主体系统设计方法进行了扩展,支持网构软件的分析、设计、实现和部署等各个阶段.该方法建立了一个通用的信任模型来描述网构软件中各个软件实体间的信任关系,并通过定制灵活的信任评价反馈策略来体现信任值的动态变化;该方法还使用有限状态自动机对网构软件中软件实体的正常行为和故障行为进行建模,并通过动态描述逻辑DDL加以描述,在网构软件运行的时候能够通过系统观测和DDL推理机动态地诊断出故障;结合具体的案例对网构软件系统的设计过程给出详细的介绍.     

利用ADS设计基于MESFET的宽带功率放大器

文章介绍了一种在无法获取器件大信号模型的情况下采用小信号法设计宽带功率放大器的方法.基于微波砷化镓场效应管,采用小信号设计方法,利用ADS软件,依据宽带功率放大器的各项指标来同步进行电路的设计、优化和仿真,设计出了满足预期期望值的宽带功率放大器.     

Very Rapid Prototyping of Wearable Computers: A Case Study of VuMan 3 Custom versus Off-the-Shelf Design Methodologies

The Wearable Computer Project is a testbed integrating research on rapid design and prototyping. Based on representative examples from six generations of wearable computers, the paper focuses on the differences in rapid prototyping using custom design versus off-the-shelf components. The attributes characterizing these two design styles are defined and illustrated by experimental measurements. The off-the-shelf approach required ten times the overhead, 30% more cost, fifty times the storage resources, 20% more effort, five times more power, but 30% less effort to port software than the embedded approach. An evaluation of the VuMan 3 design is presented to show its superior advantages in comparison to the off-the-shelf approach.     

On the design considerations of solid-state power amplifiers for satellite communications: A systems perspective

Conventional solid-state power amplifier (SSPA) design approach isolates radio frequency (RF) design from communication theory. In this paper, a unified SSPA design approach is proposed, which optimizes SSPA parameters (bias voltage and input RF signal power) to minimize total DC power consumption while satisfying received SNR constraint specified by the link budget. The effect of SSPA nonlinearity is quantified by the error vector magnitude measured at its output and the corresponding received SNR degradation is analyzed. Using the quantitative metrics for received SNR, it is possible to evaluate highly nonlinear SSPA classes such as Class-B or deep-Class AB, which are normally not considered in conventional SSPA design approach to be used in satellite communication applications.     

Rapid design space exploration by hybrid fuzzy search approach for optimal architecture determination of multi objective computing systems

Design Space Exploration (DSE) with multi-parametric objective in High Level Synthesis (HLS) involves assessing the various design points in the architecture design space to find the optimum solution for the design according to the system requirements specified. Due to the time to market pressure, the cost of solving the problem of architecture selection by exhaustive analysis is strictly forbidden. The tradeoffs linked to the selection of the appropriate design point during architecture evaluation needs careful assessment for efficient design space exploration. Further DSE requires satisfying multiple conflicting multi objective conditions such as increase in accuracy of evaluation during DSE with simultaneous speedup in the exploration process. This paper presents a novel hybrid design space exploration approach which is a combination of the Priority Factor (PF) method and Fuzzy search technique that is rapid and accurate in architecture evaluation and selection. The proposed approach for DSE when applied on a number of benchmarks yielded superior results compared to the current existing DSE approach for architecture selection. The comparison results of the proposed hybrid approach with the current existing approach for different benchmarks are shown and the speedups obtained are also presented.     

Design of a boost power factor correction converter using optimization techniques

This paper presents an approach to continuous variable design optimization of a power electronics converter. The objective of the optimization approach is to minimize the total component cost. The methodology is illustrated with the design of a boost power factor correction front-end converter with an input electromagnetic interference filter. The system design variables are first identified. The relevant system responses and component costs are then expressed as a function of these design variables. Finally, by using mathematical optimization techniques, the design variable values that minimize the total system component cost are obtained, given practical constraints on these design variables and system responses.     

A unified approach to multistage frequency-response masking filter design using the WLS technique

This paper presents a unified approach to the optimal design of sharp linear-phase finite-impulse-response (FIR) digital filters synthesized using the multistage frequency-response masking (FRM) technique. In this approach, the design of a k-stage FRM filter is achieved in a recursive manner. The minimax design problem arising at each step of the synthesis process is converted into a corresponding weighted least-squares (WLS) problem. The WLS problem is highly nonlinear with respect to the coefficients of the filter. Consequently, it is decomposed into several linear least-squares (LS) problems, each of which can be solved analytically. It is then solved iteratively by using an alternating variable approach. Numerical design examples are included to demonstrate the effectiveness of the method.