雅格美高性能DAC

数字/模拟转换器简称DAC(Digtal/Analog Conversion),是数字音响设备中的数字处理系统,包括控制系统、数字声频运算处理、数/模转换等。独立的DAC更能充分发挥数字技术的优异性能,使数字音响的重放效果,提高到更高层次,音乐重放质量可达到为高级模拟唱盘极为相似的水准,尤其对微弱信号中声音的重现,具有丰润的音色,极富音乐感。     

音箱和功放如何出好低音(上)

音响的最高境界在低音。低音大鼓的风压感、贝司的低鸣、大型交响乐的雄壮、管风琴踏板的低音域……这些都是音响杂志中描述低音重放时的音源。发出低音的乐器本身的体积相当庞大,能量非同小可。因此要图简单,用小型的音响设备来再现低音是不可能的。能真正再现这类极低频率的声音的音响设备并不多,说这样的设备正待开发也不为过。如果不是特定的低音重放设备,就会感觉到声音单薄、没有迫力、不鲜明、不清晰,就会出现这样或那样的问题。低音重放是一件非常难的事,涉及到重放的设备、系统的设置、音箱的摆位、试听间的构建等诸多因素。如果能随心所欲地控制低音就算达到了音响的最高境界。本期先介绍低音箱的结构、重低音箱选择,关于音箱设置和放大器且看下期分解。     

ALTEC346A前级与1568A、1569A功率放大器

一．Altec公司简介 著名的美国Altec lansing公司创始于1920年,当时为美国广播局下属Western Electric西电公司从事录音重放设备的开发与制造工作。该公司是世界上最早从事影音事业的先驱者,在音响设备的技术创新上成绩卓越,是美国剧场音响设备的制造商,到1929年时全美90％的舞台音响和录音重放设备均由该公司制作。     

扬声器馈线的选用

在音响系统中,连接两台音响设备（如调音台与功率放大器）的信号传输线缆称为信号线,用来把功率放大器的输出馈送到扬声器（音箱）的线缆称之为扬声器馈线。信号线末端连接的音响设备一般都具有放大能力因此,信号线的选用并不计较能量的损失,只要求传输的信号,尽量少受外界干扰,保真度高就可以了。而扬声器馈线却是音响系统中传输距离长且传输功率最大的导线。如果对扬声器馈线选用不当则会使整个音响系统的效果受到影响。 对扬声器馈线的选用,以那些音响发烧友最为讲究,甚至不惜花高价购买从国外进口的称为“音箱线”的专用传输线…     

音响里的误区(续17)

用音响欣赏音乐的房间,其听音环境在很大程度上决定了重放声音的质量,音响设备再好,如果听音环境不佳,也难以有好的声音效果,这一点常被忽略,而且还流传有诸多误区.     

光纤无源器件的技术概况和发展趋势

光纤无源器件是光纤通信中的重要器件，也是新型的电子元件。它包括光纤（缆）连接器、光纤耦合器、波分复用器、光开关、光衰减器等。本文介绍了这些器件的技术概况和发展趋势。     

音响里的误区（续5）

在广大DIY音响发烧友中,大家都在追寻电路图．以为只要找到一张好的电路图,就万事OK了,特别是对一些历史上的名机电路,更是达到了盲目迷信的境地。这恰是个误区,殊不知一台好的音响设备,其性能并不只决定于其电路,还与其选用元件,装配工艺及调试参数等有着莫大的关系。     

说说音响线材

一套音响系统能否获得良好的声音重放效果,除了与音响器材的合理选用和搭配、听音环境的声学条件以及音箱的摆位等因素有关外,系统中各种音响设备之间的连接线,对它也有一定的影响。众所周知,音响器材中各种连接导线是由金属材料制造的,金属导体是有一定的电阻的,而导体的电阻大小取决于导体的长     

信息领域中的主要新型元器件(上)

在信息领域中所用的元器件是电子工业的基础,可以说没有元器件的发展就没有电子工业的发展。它的应用非常广泛,并且可能有多种分类方法。本文将粗略地介绍一下无源元件,有源元件,同信息相关的ＭＥＭＳ器件及微传感器。 一．无源元件 无源器件包括小型继电器、片状元件、用于通信设备的陶瓷多层片状元件、声表面波（ＳＡＷ）器件以及以质结二端无源器件。其中,为了发展小型继电器,引进关键技术,有重点进行技术改造,重点发展固体继电器及智能化继电器技术。片状元件主要发展方向是进一步减小尺寸、提高精度、扩大生产。这里重点介绍一…     

国外军用阻容元件可靠性工作的进展

军用电子设备中阻容元件的可靠性对整机可靠性的影响很大。国外(主要是美国)在可靠性评估和可靠性管理方面取得了新的进展。本文介绍了国外军用阻容元件目前达到的可靠性水平。对我国如何提高军用阻容元件的可靠性提出了建议。     

Novel lossless synthetic floating inductor employing a grounded capacitor

A new lossless synthetic floating inductance circuit, employing a grounded capacitor and CC IIs as active elements, is presented which, in contrast to recently reported circuits, does not require any component-matching condition for the desired realisation. The other novel features of the circuit are use of a minimum possible number of passive components and inductance control through a single grounded resistor.     

Floating Immittance Function Simulator and Its Applications

A new floating immittance function simulator circuit is proposed using two different active elements, a dual-output second generation current conveyor (DO-CCII) and an operational transconductance amplifier (OTA). The presented circuit can realize a positive and negative floating inductor, capacitor and resistor depending on the passive component selection. Since the passive elements are all grounded, this circuit is suitable for fully integrated circuit design. The circuit does not require any component matching conditions, and it has a good sensitivity performance with respect to tracking errors. Moreover, the proposed positive and negative inductance, capacitor and resistor simulator can be tuned electronically by changing the biasing current of the OTA or can be controlled through the grounded resistor or capacitor. The proposed floating inductor simulator circuit is demonstrated by using a SPICE simulation for 0.35 μm TSMC CMOS technology. The proposed circuit consumes an average power of 1 mW using ±1.5 V supply voltages.     

我国片式元件市场研究

片式元件国内主要市场是彩电用电子调谐器和大屏幕彩电的机芯。十年来,以片式电阻器和片式电容器为主的生产线引进了３３条,共用资金约８０００万美元,但至今在所用原材料和生产技术上还存在不少问题,“洋鸡吃洋米才下蛋”的状况并无大的改观。指望我国片式元件在近期内得到大发展是不现实的,尚须在基础研究方面进行高强度投入。     

Current-mode variable frequency quadrature sinusoidal oscillators using two CCs and four passive components including grounded capacitors

This paper reports realizations of current-mode quadrature sinusoidal oscillator using only two multiple-output current conveyors (first or second generation current conveyor CCI/CCII) and four passive components including two grounded capacitors. Therefore, the circuits employ minimum number of passive components to realize a second-order sinusoidal oscillator. Three types of circuits are reported depending on the condition of oscillation and frequency of oscillation (FO). The circuits have FO controllable by either resistor or capacitor and are suitable to be used as variable frequency oscillator for different applications. All the circuits provide two explicit quadrature current outputs from high output impedance terminals. PSPICE simulation results are included to verify the workability of the proposed circuits.     

Analysis of a novel (LCR)trap-LC-RC filter with improved performance for standalone inverters

ABSTRACT

This work introduces a new passive filter structure for a pulse width modulated inverter used in standalone applications. The proposed structure consists of an additional capacitor connected across the resistance-capacitance branch of the traditional LCR filter and an additional resistor connected across the trap filter capacitor in the traditional (LC)_trap-LCR filter configuration which helps to reduce damping power loss and increase harmonic attenuation while maintaining the same overall filter size of conventional filters. A comprehensive parameter design procedure of the proposed filter is introduced which considers inverter switching frequency and choice of damping components. Further, particle swarm optimisation algorithm is newly employed in this work to minimise resonant peaking on the premise of allowable values of overall filter inductance, capacitance and resistance. Simulation and experimental results are presented to analyse the performance of the proposed filter and a comparison is established with other passive filter topologies. A five-level inverter with the proposed filter is implemented using a SPARTAN- 6 XC6SLX25 processor on an experimental set-up. The experimental results show an attractive performance of the proposed filter in providing improved inverter output waveforms, significant harmonic reduction in the high-frequency band, reduced resonant peaking, lesser harmonic distortion and lower damping power loss.     

On the implementation of the floating simulators employing a single active device

In this paper, two circuits for realizing floating inductor (FI), floating capacitor (FC) and floating frequency-dependent negative resistor (FDNR) simulators depending on the passive component selection are introduced. Both of the developed circuits employ a single active device called modified current feedback operational amplifier (MCFOA) and a minimum number of passive elements. The FIs and FCs use a grounded capacitor thus the developed circuits are very suitable for fully integrated circuit (IC) design. Also, the proposed circuits require no critical passive component matching conditions and/or cancellation constraints. The simulation results using SPICE program are also given to verify the theory to exhibit the performance of the first circuit.     

Memristor and the integral quantum Hall effect

New equations with a fractional derivative, which relate current and voltage, are obtained for an arbitrary memristor (one of four basic passive elements of electronic circuits, along with resistor, capacitor, and inductor). The physical meaning of fractional differentiation in application to a memristor is clarified. It is shown that the integral quantum Hall effect can be the physical basis of memristor’s operational principle.     

国外高可靠军用集成元件技术研究综述

介绍了国外集成薄膜电阻器、电容器及无源组件的关键工艺技术的研究情况。     

基于LTCC技术的无源器件设计方法

作为一种新型的集成封装技术,低温共烧陶瓷（LTCC）技术以其优良的高频和高速传输特性,小型化、高可靠性而备受关注。由此可见研究如何利用LTCC技术开发高性能的小型化无源器件对于无线通信产品的发展是有实际意义的。LTCC技术能充分利用三维空间发展多层基板技术,其产品在封装和小型化方面具有明显优势;LTCC技术具有损耗小、高频性能稳定、温度特性良好等特点。同时介绍了国内外LTCC元器件发展现状和趋势,以及基于LTCC技术的无源器件的设计和应用。     

3302自动零件分析仪的测量系统分析

该文以3302自动零件分析仪组成的测量系统为研究对象,制定了自动零件分析仪测量系统分析计划,采用均值-极差法对测量系统的重复性和再现性的分析步骤、计算过程、计算结果做了详尽的剖析和讨论.认为该测量系统的偏倚、线性和稳定性能满足要求,测量电感、电容、电阻的重复性与再现性指标分别为6.7%、2.1%、20.1%,均小于30...