The concept of time-average-frequency and mathematical analysis of flying-adder frequency synthesis architecture

Flying-Adder frequency synthesis architecture is a novel technique of generating frequency on chip. Since its invention, it has been utilized in many commercial products to cope with various difficult challenges. During the evolution of this architecture, the issues related to circuit- and system-level implementation have been studied in prior publications. However, rigorous mathematical treatment on this architecture has not been established. In this paper, we attempt to explore and understand the signal characteristics and frequency domain behavior of this architecture through mathematical analysis. In the meantime, the underlying concept associated with this architecture, time-average-frequency, is formally introduced.     

A "Flying-Adder" frequency synthesis architecture of reducing VCO stages

The "Flying-Adder" architecture is a frequency and phase synthesis technique that is based on a voltage-controlled oscillator (VCO) of multiple delay stages. Since the invention of this architecture, various improvements have been made during many implementations of this technique. One of the remaining issues is to reduce the number of delay stages inside the VCO for the benefit of low power consumption and easy design/layout implementation. This paper presents a modified version of the architecture, by utilizing the scalability presented by Xiu and You, 2002, to achieve this goal. The modified architecture can also be used to improve the number of synthesizable frequencies. The tradeoff for this architecture of reduced-delay-stage VCO is the circuit speed     

Discussion on the general oscillation startup condition and the Barkhausen criterion

The Barkhausen criterion has been widely used to determine the oscillation startup condition. However, we propose it is only partially correct. The general oscillation condition and the relation between the general oscillation condition and the Barkhausen criterion are reviewed in this paper. The oscillation frequency related to the general oscillation startup condition is also presented.     

An X-band LSA Amplifier

Linear reflection gain has been observed from a GaAs diode oscillating in the LSA mode with gain occurring at a frequency not harmonically related to the fundamental oscillation frequency. The characteristics of the amplifier are presented together with measurements of the circuit load as seen by the device. The mechanism of operation is also discussed.     

超声技术在半导体行业中应用探讨

晶片的洁净程度直接决定了晶片的价值,而晶片最前端工艺就是清洗。现代化超声技术的应用可让晶片更洁净。超声波清洗的功率、频率、尺寸、安装方式的选择都与晶片清洁程度有着密切关系。主要对超声波的原理和频率的选定进行了介绍。     

Degradation and breakdown of thin silicon dioxide films underdynamic electrical stress

Thin oxide MOS capacitors have been subjected to dynamic voltage stresses of different characteristics (shape, amplitude and frequency) in order to analyze the transient response and the degradation of the oxide as a function of the stress parameters. The current transients observed in dynamic voltage stresses have been interpreted in terms of the charging/discharging of interface and bulk traps. As for the oxide degradation, the experimental data has been interpreted in terms of a phenomenological model previously developed for dc stresses. According to this model, the current evolution in voltage stresses is assumed to be related to the oxide wearout. The evolution of the current during bipolar voltage stresses shows the existence of two different regimes, the degradation being much faster at low frequencies than at high frequencies. In both regimes, the frequency dependence is not significant, and the change from one regime to the other takes place at a threshold frequency which depends on the oxide field. These trends are also observed in time-to-breakdown versus frequency data, thus suggesting a strong correlation between degradation and breakdown in dynamic stresses. The experimental results are discussed in terms of microscopic degradation models     

A Superconductor THz Modulator Based on Vortex Flux Flow

A terahertz modulator based on the Type-II superconductor flux flow oscillator has been proposed. Analytical calculations are presented and the effects of intrinsic and extrinsic parameters such as disorder strength of crystal, penetration depth, frequency, and amplitude of the modulated current on the radiation power spectrum have been studied. The proposed structure also exhibits a mixer-like behavior, in the sense that its output harmonics range from the washboard frequency up to the superconductor gap frequency, so the input signal is practically mixed with the washboard frequency and its harmonics. The modulation index for each harmonic of this modulator has also been investigated. This well-featured modulator has a potential to be used in next-generation terahertz integrated transceivers.      

An analytical maximum toggle frequency expression and itsapplication to optimizing high-speed ECL frequency dividers

A novel method is used to analyze static and regenerative frequency dividers by relating their performance to that of the constituent EXCLUSIVE-OR (XOR) gates. It is found that the behavior of the propagation delay of XOR gates is quite linear, and this allows the derivation of a propagation delay expression for XOR gates using a sensitivity analysis. The validity of the expression is checked by comparison with SPICE simulations and with results from the literature, and agreement to 10% is obtained. It has been found that this expression can be used to accurately predict the maximum toggle frequency of frequency dividers. Using this expression, it has also been verified that the maximum toggle frequency of regenerative frequency dividers is about twice as high as that of static frequency dividers. In order to optimize frequency dividers, figures of merit for frequency dividers realized in silicon and AlGaAs-GaAs technologies are proposed     

GaAs数字单片电路的计算机模拟

本文在开发并确立通用电路分析程序SPICE3A7的GaAs MESFET模型及相应模型参数提取方法的基础上,对GaAs MESFET器件及相关BFL.单元电路进行了直流和瞬态的计算机模拟和部分优化,取得了较好结果;并对研制中的分频器电路设计进行了计算机研究.     

一种实现高精度稳定Zeeman激光频差的方法

为了使双频激光干涉仪的高精度和可靠性能够在当前急需解决的大尺寸高精度同轴度、直线度测量方面有效的发挥出来,有必要在双频激光干涉仪的信号处理方面采用比相技术,为此,需要稳定Zeeman激光的频差.本文提出一种基于8098单片机系统的智能化稳频差方案,不但保证了频差的稳定性,而且每次开机还能自动搜寻频差极值,从而保证了光频的复现性.系统经过实验验证,频差变化小于5kHz/5h,工作稳定可靠,可以满足比相的要求.     

Theory of oscillator instability based upon structure functions

Structure functions are apparently unfamiliar to most engineers and the unifying role they play in oscillator instability theory has largely gone unrecognized. This paper introduces and places into perspective the role which Kolmogorov structure functions have in theory. It is demonstrated that the rms fractional frequency deviation (phase accumulation) introduced by Cutler and Searle is related to the first phase structure function; the two-sample Allan variance is related to the second phase structure function. In addition, it is shown how the two-sample Allan variance is related to the rms fractional frequency deviation under suitable conditions. The L-sample Allan variance is also identified in terms of the first phase structure function; it is shown to be an asymptotically unbiased estimator of the rms fractional frequency deviation squared if the latter existL The utility of higher order structure functions of frequency and phase in the theory of instability is also demonstrated; in particular, how the frequency drift and "flicker"-type noise convergence problems can be overcome.     

Ti-TiO2 gated MOS diode light sensor

This paper explores the possibility of improving the performance of a resistive TiO₂-Ti gated MOS diode as a light sensor. The original device proposed by Whelan has a limitation on the maximum useful scan frequency to several hundreds of Hz. In this paper, a new construction was proposed to improve the maximum scan frequency and extend this limitation to about 10 KHz. It is also shown that the frequency can be further improved to about 1 MHz by reducing the gate resistance and capacitance. The limitation in the growth cycle is mainly due to charging of the gate electrode and output resistance. No attempt has been made for the optimization of the device design. The resolving power was also been considered.     

Instantaneous Frequency, Mean Frequency, and Variance of Mean Frequency Estimators for Ultrasonic Blood Velocity Doppler Signals

The relationship between the instantaneous frequency and the mean frequency of ultrasonic Doppler signals in blood velocity measurements is discussed. The probability distribution density for the instantaneous frequency is calculated. The time interval histogram (TIH), which has been used to characterize the Doppler signal, is found to be an approximation of this probability density. The probability density will also describe the output of phase-lock loop analysis of the Doppler signal. The variance of mean frequency estimators is calculated, and the implication of this for practical estimators is discussed. The effect of hard limiting of the signal on the estimator performance is also discussed.     

具有陷波功能的超宽带缝隙天线的设计与研究

提出了一种具有陷波功能与分形调谐支节的新型超宽带缝隙天线.该天线的结构类似于一般的微带缝隙天线,通过采用分形调谐支节引入半波长谐振结构,使得该天线不仅具备了超宽带缝隙天线的优点,还具备灵活可调的陷波功能.通过计算、测量和尺度放大实验,充分考察了天线的频域特性.实验结果表明该天线的工作频带为2.66～10.76 GHz,在4.95～5.85 GHz频段上具有陷波功能,同时具有相对稳定的辐射方向性和近似的全向特性.该研究对设计小型超宽带天线具有一定的价值.     

薄膜体声波谐振器调频工艺研究

薄膜体声波器件具有体积小及性能高等优势,相关产品已被广泛应用于移动通信市场。薄膜体声波谐振器(FBAR)电极层和压电层等声学层的厚度、材料是影响谐振频率的主要因素。该文分析了FBAR调频的必要性、原理及扫描刻蚀的工作方式,研究了调频层薄膜在不同刻蚀功率时对器件频率的影响。通过对FBAR器件进行调频,频率均匀性提高了6.5倍,频率分散性得到显著改善。     

小型宽带平面天线设计

通过论证自互补结构天线的输入阻抗基本与频率无关的角度证明了该天线具有超宽带特性。实际制作了一个同类型的天线,经测试,该天线在300 MHz~3 GHz的频带内,电压驻波比<3,证实了该类天线的超宽带特性。     

基于射频识别技术的全自动车辆管理系统的分析与研究

介绍自动识别技术和射频识别技术的概念,详述了射频识别技术的工作原理、系统组成、功能特点,基于这种技术设计了一种全自动车辆管理系统,给出了系统的总体设计、工作原理及功能特点,最后举例说明了系统射频识别码的组成,同时对这种全自动车辆管理系统在不同场合的应用情况进行了详细的对比说明.     

压电复合换能器的结构对其频率特性的影响

研究了多模耦合宽频带复合换能器,结果发现,这种换能器在空气中的纵弯振动具有明显的规律性.针对1-3型压电复合材料,采用有限元法研究了压电陶瓷体积分数对换能器共振频率的影响,并研究了换能器共振频率与其几何尺寸间的关系.结果表明,换能器共振频率与压电陶瓷体积分数及其几何尺寸有关,即随压电陶瓷体积分数增加,共振频率增大;换能器前盖板几何尺寸越大,共振频率越小,纵振基频与弯振基频间距亦随之减小.     

辽源双频网研究与优化方案

随着GSM用户量的不断增长,GSM900单频网络已经无法承载日益增长的高话务,1800网络的引入缓解了GSM900话务负荷,但也面临着话务不均衡的现象。一方面为了提高900M与1800M载频的利用率,更好地使用有限的网络资源;另一方面为了降低拥塞率,提升网络指标,中国联通辽源分公司适时进行为期42天的900M与1800M的话务分担相关优化。     

Note on the relationship between the domain-transit frequency and the cavity-controlled frequency of thin Gunn devices

Some measurements on thin Gunn devices mounted in cavities covering the range 7?20GHz are reported. For any particular device, it has been found that VBf is approximately constant, where VB is the bias voltage which gives maximum r.f. output at the frequency f. This observation has been related to the domain-transit frequency.