基于OTA的文氏电桥振荡器

提出了基于ＯＴＡ的文氏电桥振荡器，详细分析了该振荡器的原理，得出了起振条件和振荡频率。     

基于OTA的文氏电桥振荡器

提出了基于OTA的文氏电桥振荡器，详细分析了该振荡器的原理，得出了起振条件和振荡频率。     

文氏电桥振荡器主振回路最佳m参数的探讨

文氏电桥正弦波振荡器以其性能优良、结构简单而被广泛采用.本文拟对主振级桥路m参数的选择作一些比较深入的讨论. 对于文氏电桥振荡器的电桥回路(图1),实用中C_1=C_2=C,又令m=R_1/R_2,则有(见萨柯夫著:选择性RC系统的理论和计算,中译本,第71～72页,以后再提本书时,仅注明页数):     

综合接入将获得新生

CLEC们的衰落似乎为综合接入设备鸣响了丧钟，因为这些竞争性本地运营商是捆绑业务的主要购买者。但据Yankee Group预测，综合接入设备市场将会反弹，尤其对于只需1～2条T1线路的小办公室用的低端综合接入设备更是如此。但目前，传统本地运营商（ILEC）和交换电信运营商（IXC）是综合接入设备的主要买主。 虽然TDM是每个厂商都支持的主要网络接口，然而目前越来越多的高级网络技术也开始引入综合接入设备中。Yankee Group的分析专家Daniel Klein预测，受Adtran和Vina等公司的低端设备销量的驱动，整个综合接入设备市场将在2007年…     

从正反馈级获得迟滞的非稳态多谐振荡器

很多设计都采用基于逻辑元件的非稳态多谐振荡器,最简单的办法是围绕一个单反相施密特触发转换器的RC反馈回路(图1)。输出端将电容充电至较高的开关阈值,在该点上输出切换至其相反状态,阈值转换为一个不同值,而电容的充电电流反向。当电容的     

光刻设备在特定应用中获得新生

由于我们一直致力于预测集成电路技术的未来发展．这就容易忽视那些老代技术潜在的巨大市场的需求。但令人欣慰的是．包括248纳米光刻系统在内的老代的技术平台正被重新改造，进而投入不断成长的市场接受挑战。     

利用KTP光学参量振荡器获得可调谐人眼安全激光

报道了用 Nd:YAG激光器二次谐波 532 nm抽运 KTP光学参量振荡器 (OPO)的实验结果 ,获得了对人眼安全的 1.53～ 1.84 μm和近红外 0 .74～ 0 .82 μm调谐激光输出 ,重复频率 10Hz。 OPO谐振腔采用π抽运结构 ,获得的最高总输出能量为 93m J,最高能量转换效率为 16 .5% ,并测量了光束质量和线宽。     

振荡器

低抖动时钟振荡器扩大工作温度范围 T3312/3212时钟振荡器工作温度范围是-40℃～85℃,在产生20～100MHz时钟信号的条件下,抖动小于5ps(rms)。T3312在3.3V工作电压下最大工作电流35mA,T3212在5V工作电压下工作电流45mA。 器件可保持45:55的波形对称度,上升时间和下降时间的典型值为4ns,在整个工作温度范围内频率稳定度±50ppm。振荡器兼容TTL电平和HCMOS电平,采用表面封装形式,大小为5×7×1.9mm。(批量单价8.75     

Fractional-order Wien-bridge oscillator

The classical Wien-bridge sinusoidal oscillator is studied, when both of the capacitors of the oscillator acquire a fractional order. Accordingly, the Wien oscillator is described by a set of fractional-order nonlinear differential equations. It is shown that sinusoidal oscillations are preserved but the phase-shift between the waveforms of the two state variables and the frequency of oscillation both depend on the fractional-order, leading to a significant advantage over the integer-type Wien oscillator. Findings are validated via numerical simulations     

Modified Wien-bridge oscillator for chaos

A nonlinear Wien-bridge based circuit generating chaotic oscillations is reported. The generator contains a single opamp and a single nonlinear device displaying a current saturation characteristic. The oscillator is described by a set of three ordinary differential equations. Experimental results are included demonstrating the circuit performance     

On modified Wien-bridge oscillator and astable oscillator

The present article is related to the recently published paper given in (Abuelma’atti and Khalifa, Analog Integr Circuits Signal Process, 73:989–992, 2012), which depicts the possible relation between the modified Wien-bridge circuit used by the authors of references (Singh, Analog Integr Circuits Signal Process 48:251–255, 2006; Singh, Analog Integr Circuits Signal Process, 50:127–132, 2007; Singh, Analog Integr Circuits Signal Process, 62:327–332, 2010; Wangenheim, Analog Integr Circuits Signal Process, 66:139–141, 2011; Martinez-Garcia et al., Analog Integr Circuits Signal Process, 70:443–449, 2012), and the comparator-based relaxation oscillator. In particular, in the referenced Mixed Signal Letter (Abuelma’atti and Khalifa, Analog Integr Circuits Signal Process, 73:989–992, 2012), the authors assert that the modified Wien-bridge oscillator circuit under discussion, used previously in the aforementioned referenced articles, can behave as a sinusoidal oscillator only at relatively high frequencies when the operational amplifier can be considered non-ideal. In addition, at relatively low frequencies, when the operational amplifier can be considered ideal, the same circuit would behave as a relaxation oscillator with a square wave output rather than a sinusoidal output. However, this paper reveals that this assertion is not strictly correct, because in both cases (in low and high frequencies), the generated waveform at the circuit output is a sinusoidal signal, with the possibility of be cut out, depending on proper circuit dimensioning (according to the oscillation criterion) as well as the oscillation frequency and the properties of the amplifier (slew rate, and frequency response).     

Chaos generator via Wien-bridge oscillator

A new chaos generator obtained by designing a controller for the celebrated Wien-bridge oscillator is presented. The chaotic attractor exhibited in this generator is globally attractive and stable in the Liapunov sense and is more practical for engineering problems     

Composite-amplifier Wien-bridge oscillator with improved limit-cycle stability

The problem of undesirable low-frequency oscillation which may occur in oscillators with composite amplifiers is discussed. The article shows how the Wien-bridge oscillator proposed by Carlosena et al (1990) should be modified in order to avoid such oscillation and ensure stable operation of the oscillator and good properties of the sinusoidal waveform generated.<>     

A new single MCCCDTA based Wien-bridge oscillator with AGC

This paper presents a new current-mode Wien-bridge oscillator with automatic amplitude control. The oscillator only employs single MCCCDTA as the active element and provides two current outputs with small distortion from high output impedances. Its oscillation condition and frequency can be tuned electronically, linearly and independently through tuning bias currents of MCCCDTA. The circuit simulation results are in agreement with theory.     

改进型文氏桥混沌振荡器：建模、分析 与实验

通过引入二极管—电感并联网络实现了一种改进型文氏桥混沌振荡器。借助于二极管含寄生电容的分段线性模型,有效解决了该混沌电路的动力学建模问题。基于系统模型,研究了系统的平衡点及其稳定性,利用数值仿真和硬件实验手段,揭示并验证了随系统参数变化的动力学行为。结果表明,新提出的改进型文氏桥混沌振荡器有着简单的电路结构,存在混沌和周期等非线性动力学行为。     

Computer reborn

Many good things from the good old days are gone- children playing outside, fruit that tastes better than it looks, luxurious air travel. But how could anyone get nostalgic about yesterday?s big-iron computers, which were worse than today?s handhelds by every measure?     

Wien-bridge chaotic circuit with comparator

A Wien-bridge-based circuit generating chaotic oscillations has been designed and investigated both numerically and experimentally. The oscillator contains an operational amplifier, a Wien-bridge used as a resonance loop, an additional RC inertial circuit, and a comparator employed as a nonlinear device. The waveforms and the Lyapunov exponents are presented. The synchronisation properties have been investigated     

The Manchester baby reborn [Small Scale Experimental Machine]

A program was laboriously inserted and the start switch pressed. Immediately the spots on the display tube entered a mad dance. In early trials it was a dance of death leading to no useful result. But one day it stopped and there shining brightly in the expected place, was the expected answer. So Prof Sir Frederic Williams described how a stored program successfully ran on a computer for the first time in the world on 21 June 1948. That historic event was one of the major steps in ushering in the information age, the second industrial revolution. The countless millions of people who use a computer today would find the principle of that event, to load and run a program in a universal machine, exactly as they do every day. And no earlier computer, for example the huge ENIAC machine at the University of Pennsylvania, could claim that 'likeness'. The computer was the Small-Scale Experimental Machine (SSEM) at Manchester University, later enlarged to become the Manchester Mark 1. That computer was dismantled and the parts dispersed in 1951-52 to be replaced by an engineered version, the Ferranti Mark 1, the first commercially delivered computer in the world. Fifty years ago, the first successful running of a stored program marked the beginning of a new era in computing. The author describes how the machine responsible, Manchester University's “Baby”, has been rebuilt to mark the anniversary