Architectures and design considerations for wireline ΣΔ modulators beyond ADSL

In this paper we discuss design considerations for sigma–delta modulators (ΣΔMs) aimed at high-linearity high-speed A/D conversion, as required in emerging wireline access applications. In order to achieve resolutions in the range of 12–15 bit with sufficiently low oversampling ratio, we analyze the performance of a family of high-order cascade architectures in a low-voltage deep-submicron scenario. We show that, after proper architecture selection, guided by a simple power estimation method, these ΣΔMs are good candidates to achieve ADSL performances in coming CMOS processes. Experimental results on a prototype for ADSL+ applications designed in 2.5-V 0.25-μm CMOS suggest the possibility of programming or reusing the design for other telecom applications, thanks to the easiness to expand or shrink this family of cascade ΣΔMs to other orders. Estimated performance of the adapted prototype for ISDN, SDSL, and VDSL applications provides promising results.     

High resolution data conversion via Σ-Δ modulators and polyphase filters: a review

This paper takes a brief look at conventional data conversion schemes, setting the scene for the inevitability of the Sigma-Delta (Σ-Δ) approach in conjunction with digital decimation filtering techniques, particularly focusing on single-loop single-bit higher-order modulators coupled with allpass polyphase multistage decimation filters which yield high-fidelity data converters for relatively narrow-band signals that may be used for instrumentation data acquisition and measurement applications. Practical integrated implementation guidelines, with the associated advantages, disadvantages constraints and trade-offs, are also included in this paper.     

一种廉价实用的双积分A/D转换器

介绍用51单片机和通用分立器件构成的双积分A／D转换器，文中给出了详细的源程序清单。     

Systematic design and modelling of high-resolution, high-speed pipeline ADCs

This paper describes a suitable mathematical model for the design of high-speed, high-resolution pipeline ADCs. The effect of capacitor mismatch and finite amplifier bandwidth and gain on the converter INL and DNL are accurately modelled. On the basis of this model a design optimisation method is provided.     

Elimination of drift-like errors in intelligent cyclic A/D converters

The paper presents a new method of elimination of influence of drift-like errors in so called intelligent cyclic A/D converters, in particular, errors caused by drifts (droops) of voltage at the output of sample-and-hold blocks. The method is based on application of the extended multi-dimensional algorithm, which estimates simultaneously values of the input sample and drift rate. Implementation of the extended algorithm in the intelligent cyclic A/D converters requires only insignificant changes in the digital part of the converter and does not increase their production costs. The motivations to these investigations resulted from practical realizations of the intelligent cyclic A/D converter in CMOS technology and difficulties in design of a precise sample-and-hold circuit. The results of selected simulation experiments related to analysis of influence of a droop rate on the final performance of the intelligent cyclic A/D converters employing the standard (one-dimensional) and extended algorithms are discussed and compared in the paper. The results of experiments show that application of the proposed solution enables efficient functioning of the converters even in the presence of relatively large drifts.     

智能散热器单片机控制系统的设计与实现

温度控制是众多工业控制中重要的组成部分,散热器则是其中不可缺少的一环。介绍一款智能散热系统的设计,其核心以8051为主控制器、AD590集成温度传感器作为采集器、ADC0809为A／D转换器,其可实现耗能低,可靠性高,抗干扰能力强,使用方便等特征。     

Exploring the transitional impacts of a 2D to 3D design environment for the development of torque converters

This paper presents the internal process changes required for the transition from a 2D to a 3D design environment for the development of torque converters at LuK, Inc. Recently, since American automotive customers have demanded that suppliers provide torque converter designs and assembly models using all 3D design packages, the change of the design environment to a 3D one is mandated. For this reason, the work described in this paper is concerned with how to examine each area of LuKs product development cycle and develop a flowchart detailing the steps involved in taking a product from a customer request through the design, demonstrate and launch phases of the product. The case study conducted in the work can be used as a guideline for establishing the influences of a product development cycle due to a CAD environment upgrading and/or a new adaptation which is deemed inevitable in the long run. In light of this study, the impacts to the R&D process can be dealt with way in advance to reduce or eliminate the potential drawbacks due to the mandated transition of design/manufacturing environments.     

Evidence of multimicrometric coherent γ′ precipitates in a hot‐forged γ–γ′ nickel‐based superalloy

This paper demonstrates the existence of large γ’ precipitates (several micrometres in diameter) that are coherent with their surrounding matrix grain in a commercial γ–γ’ nickel‐based superalloy. The use of combined energy dispersive X‐ray spectrometry and electron backscattered diffraction (EBSD) analyses allowed for revealing that surprising feature, which was then confirmed by transmission electron microscopy (TEM). Coherency for such large second‐phase particles is supported by a very low crystal lattice misfit between the two phases, which was confirmed thanks to X‐ray diffractograms and TEM selected area electron diffraction patterns. Dynamic recrystallization of polycrystalline γ–γ’ nickel‐based superalloys has been extensively studied in terms of mechanisms and kinetics. As in many materials with low stacking fault energy, under forging conditions, the main softening mechanism is discontinuous dynamic recrystallization. This mechanism occurs with preferential nucleation on the grain boundaries of the deformed matrix. The latter is then being consumed by the growth of the newly formed grains of low energy and by nucleation that keeps generating new grains. In the case of sub‐solvus forging, large γ’ particles usually pin the migrating boundaries and thus limit grain growth to a size which is determined by the distribution of second‐phase particles, in good agreement with the Smith–Zener model. Under particular circumstances, the driving force associated with the difference in stored energy between the growing grains and the matrix can be large enough that the pinning forces can be overcome, and some grains can then reach much larger grain sizes. In the latter exceptional case, some intragranular primary γ’ particles can be observed, although they are almost exclusively located on grain boundaries and triple junctions otherwise. In both cases, primary precipitates have no special orientation relationship with the surrounding matrix grain(s). This paper demonstrates the existence of high fractions of large γ’ precipitate (several micrometres in diameter) that are coherent with their surrounding matrix grain, in a commercial γ–γ’ nickel‐based superalloy. Such a configuration is very surprising, because there is apparently no reason for the coherency of such particles.     

三相交流同步器信号的数字化处理

介绍三相同步器信号的作用及特征,推出将模拟三相同步器信号转换为数字信号的两种方法,并给出电路及流程图.     

基于S3C2410X振动监测系统的设计

介绍了一种新型、实用、可靠的振动监测系统的硬件设计与软件设计。系统采用S3C2410X为控制核心，通过分析由LTC2414采集到的被测设备振动加速度信号监测设备工作状态。详细论述了系统振动信号的采集、处理电路的设计以及系统软件结构与功能，最后对系统的信号处理提出改进措施。系统已在实践中得到应用，达到了设计标准。     

计算机辅助集成电路的老化

概要叙述集成电路老化的意义,以及采用计算机辅助的方法进行元器件的老化实例。     

应用新型A／D—D／A器件的数据采集系统

叙述了由AD1674和AD669构成的一种性能优异的IBMPC系列微机数据采集和控制系统、并给出了一个实用软件。     

3 mm波便携式辐射计数据采集与测试系统

在室内和室外环境下,W波段的辐射计能够有效地检测隐匿在厚外衣下面的金属和非金属武器.针对隐匿武器检测问题,在毫米波辐射计的理论基础上,开发了一种基于USB2.0接口的3 mm波便携式辐射计数据采集与测试系统.并给出了详细的硬件设计方案,实现了所有数据的自动采集、传输、测试和显示.最后通过实验验证了该方案是可行的,实现了隐匿武器检测系统的小型化和便携化.     

一种新型高可靠性甲烷传感器设计

介绍以AT89LV51单片机构成的高精度、低功耗、高可靠性、智能型甲烷传感器.考虑到井下的复杂情况,传感器设计充分考虑了本安特性和实用性.传感器以数字芯片为核心,提高了检测精度,减小了仪表体积.采用XICOR公司的SPI接口看门狗EEROM芯片、X5045芯片,使系统更加稳定、可靠.方便和PC机通信,便于井下工人随身携带,而且抑制了安全事故的发生.     

7(1/2)位A/D转换器的研制

为满足高精度电压测量的要求 ,研制了电荷平衡与单斜相结合的多斜式模数转换器。分析了复合运放提高性能的原理 ,利用两运算放大器设计了高性能复合放大器 ,以构成理想的积分电路。在对输入电压积分的同时 ,不断释放标准单位电荷量 ,以形成模数转换器的电荷平衡过程 ,并通过计数取得高位读数。断开输入后 ,连续释放剩余电荷以形成单斜过程 ,并取得低位读数。通过高低位读数的合成及采用合理的校正措施 ,模数转换器的分辨率达到七位半以上     

一种自制实用型D／A的工作原理与特性分析

介绍了一种自身D／A的硬件组成和它的工作原理,并通过实测值分析了它的工作特性。     

一种基于DSP的通用型数据采集与预处理系统

设计了以通用型数字信号处理器DSP芯片为主体的数据采集和预处理电路。采集到的信号经调节电路进行滤波，幅度变换之后，接入并行A/D芯片THS10024。经A/D变换后的数字信号接入DSP芯片TMS320VC5402，在C5402中进行预处理后经多通道缓冲串口与PC机串口（RS-232）相连送入PC机，然后通过自行编写的软件把接收到的数据文件进一步处理。在硬件设计上充分考虑了分析仪器的共同特征，在通用型数据采集方面有一定的参考价值。     

工控机在虚拟仪器设计中的应用

本文介绍了虚拟仪器的概念和特点,采用工业控制计算机实现了虚拟仪器的设计。     

一种高速冲击测试仪的研制

该文介绍了一种基于FPGA及多片A／D转换器的新式高速冲击测试仪，可实现时间一应力、时间一位移及位移一应力等曲线的记录，在解决冲击断裂性能方面具有较高的应用价值。     

基于89C52单片机的微电压信号源设计

介绍一种采用单片机控制的数字式微电压信号源的设计原理，提出了用精密分压和反馈补偿方法产生高精度、高分辨率直流电压信号的方法，并给出了主要的电路图。