用于数字电视接收机中PGA的设计

本文采用新型的电流模放大器和可编程的电阻反馈网络设计了一种高线性度的可编程增益放大器(PGA),单级的电压增益范围为0～20dB,增益步长0.5dB,3dB带宽1.7MHzMHz,两个输入谐波(tone)的频率为0.2MHz和0.3MHz,输出摆幅为峰峰值1V时,IM3大于60dB.在3.3V电源电压时功耗为2.38mW.     

Synthetic bandwidth method and experimental research based on a wideband multi-channel SAR

Synthetic bandwidth technique is used to increase frequency bandwidth of the system and provides an effective way to achieve the ultra high resolution in the field of Synthetic Aperture Radar (SAR). But in the actual SAR system, the synthesis result will be seriously deteriorated by the inner-channel and inter-channel phase error. A frequency domain synthetic bandwidth method based on transfer function extracting technique is proposed in an actual SAR system which consists of single wideband transmit channel and 8-way down-conversion receive sub-channels. The method can accurately get the amplitude and phase characteristics of the sub-channel and compensate the amplitude-phase errors. The final experimental results demonstrate the validity and feasibility of the method and the range resolution down to 0.1 m is obtained.     

一种低抖动、宽调节范围的带宽自适应CMOS锁相环

提出了一种低抖动、宽调节范围的带宽自适应CMOS锁相环.由于环路带宽可根据输入频率进行自动调节,电路性能可在整个工作频率范围内得到优化.为了进一步提高电路的抖动特性,在电荷泵电路中采用匹配技术,并在压控振荡器中应用电压-电压转换电路以减小压控振荡器的增益.芯片采用SMIC 0.35μm CMOS工艺加工.测试结果表明该锁相环电路可在200MHz～1.1GHz的输出频率范围内保持良好的抖动性能.     

Bootstrap-based bandwidth choice for log-periodogram regression

Abstract.  The choice of the bandwidth in the local log-periodogram regression is of crucial importance for estimation of the memory parameter of a long memory time series. Different choices may give rise to completely different estimates, which may lead to contradictory conclusions, for example about the stationarity of the series. We propose here a data-driven bandwidth selection strategy that is based on minimizing a bootstrap approximation of the mean-squared error (MSE). Its behaviour is compared with other existing techniques for optimal bandwidth selection in a MSE sense, revealing its better performance in a wider class of models. The empirical applicability of the proposed strategy is shown with two examples: the widely analysed in a long memory context Nile river annual minimum levels and the input gas rate series of Box and Jenkins.     

Two models of two-dimensional bandwidth problems

The two-dimensional bandwidth problem is to embed a graph G into an n×n grid in the plane such that the maximum distance between adjacent vertices is as small as possible. Here, the “distance” has two different meanings: the L₁-norm distance and L_∞-norm distance. So we have two models of two-dimensional bandwidth problem. This paper investigates the basic properties and relations of these two models. Some lower bounds, upper bounds, and exact results are presented.     

Spectral deconvolution applications for colorimetry

Deconvolution based on the Richardson‐Lucy algorithm, recently suggested to be an effective method of reducing instrumental broadening effects in radiometric spectra, is applied to two examples relevant to colorimetry. The first is chromaticity measurement of light‐emitting diodes, where results are compared with more traditional weighted‐mean bandwidth correction. The second is accurate calibration of the wavelength scale of a medium‐resolution array spectrometer. Deconvolution is shown to be an effective tool in both cases. © 2013 Wiley Periodicals, Inc. Col Res Appl, 39, 430–435, 2014     

雷达跟踪系统的随机干扰自适应

热噪声和阵风是雷达角跟踪系统中的两个主要随机干扰源.本文首先将问题公式化为一 个以热噪声误差和阵风误差的平方和为指标的最优伺服过零频率的问题,然后将该过零频率 表示为可测量的接收机自动增益控制电压和平均风速的函数,从而综合出拟增益排表自适应 控制器.并通过数学分析和现场实验证实了这种拟增益排表自适应伺服系统的优越性.     

Delta互连网有效存贮器带宽性能分析

本文运用概率分析方法，详细地分析了拥有优先级的Ｄｅｌｔａ网有效存贮器带宽的性能，获得的有效带宽模型基于访存请求均匀分布于各存贮器模块中，结果表明：优先级并不影响整个Ｄｅｌｔａ互连网有效存贮器带宽的性能。计算机模拟的结果也验证了理论分析的有效性。     

合理确定测试系统频响特性之重要性

本文简述了测试系统及其组成，并以实例介绍了影响系统频响的几个主要环节，进而说明了测试频响特性的重要意义。     

改善锁相频率合成器性能的一种有效方法

锁相频率合成器是现代频率合成器的一种主要型式，其性能主要取决于锁相环路的参数与调整状态，提高频率合成器的性能，有重要的实际意义，本文提出了一种在环路滤波器中加补偿电容来改善频率合成器性能的方法；并给出了现代锁相频率合成器的典型电路，环路参数的设计与选择及补偿后性能改善的实验结果。