便携式数据采集系统中自适应抗混叠滤波器的设计

针对设备监测与故障诊断系统中便携式数据采集系统的设计要求，采用单片8阶椭圆低通滤波器MAX293设计了向AD端集成的内置抗混叠滤波器。提出了独特的自适应抗混叠滤波方案，阐述了其在数据采集过程中的实现原理，设计了相应的硬件实现电路，并给出了滤波过程中非线性相移误差的软件校正方法。     

适用于复合视频和S端子的双向视频滤波器／缓冲器 采用了DirectDrive技术,可在单电源系统中实现低功耗

MAX7481／MAX7482为双向视频滤波器／缓冲器，可为复合视频（CVBS）以及S端子的回放模式提供重建滤波器和线路驱动缓冲器，同时还为录像模式提供抗混叠滤波器。     

一种分析和设计抗混叠滤波器的方法

信号采集通道中,一般采用高阶抗混叠滤波器来消除频率混叠现象,这同时也增加了滤波器设计难度。为有效降低滤波器设计的难度,在详细分析并讨论了抗混叠滤波器的陡度、阶数与信号抽样频率以及A/D转换器的分辨率之间的内在关系后,提出了抗混叠滤波器、抽样频率和A/D转换器三者之间合理权衡设计的方法。该分析方法为抗混叠滤波器乃至信号采集通道的设计提供了十分有益的参考。     

一种抗混叠滤波器的设计

针对信号采集时,频率混叠现象的发生,为了能够有效地提取有用信号,本文介绍了滤波器的设计原理。通过分析混叠现象产生的原因,探讨了几种常见滤波器的特点并进行了比较;最后设计了一种基于二阶巴特沃斯带通抗混叠滤波器。通过仿真结果可以得出,该滤波器具有通带衰减特性平坦,能够有效避免混叠现象发生,为工程实践提供了可靠的理论指导。     

高速高精度ADC的驱动电路

本文分无源和有源抗混叠滤波电路两种情况,分析高速高精度数据采集系统对放大器驱动能力的要求,指出习惯上的无源抗混叠滤波器已难以满足精度要求和对放大器容性负载的驱动能力过于苛刻,有源抗混叠滤波器能够较好地满足驱动要求,但对放大器仍有较高的要求.     

抗混叠塔型变换的构造

 针对Contourlet变换存在的频谱混叠,提出了一种抗混叠塔型变换,即Non-aliasing Pyramidal Transform-NA-D变换.NAP变换由抗混叠塔式滤波器组(Non-aliasing Filter Banks:NPFB)和方向滤波器组(Directional Filter Banks:DFB)组成,NPFB首先将图像分解为多个不同分辨率的细节子带和一个低频子带,DFB再将各细节子带分解为方向子带.通过设计满足Nyquist采样定理的滤波器,NA-D变换有效地抑制了Contourlet变换的频谱混叠,基函数不仅具有"多分辨率"、"多方向"、"局域性"等特性,满足各向异性尺度关系,而且空频域正则形和局域性均明显优于Contourlet变换.硬阈值去噪实验的结果表明,NAP变换能够更为稀疏的表示图像,并在去噪性能上较Contourlet变换有较大提高.     

八阶低通椭圆型开关电容滤波器及其应用

滤波器是电子电路中应用最广泛的器件之一,从简易的电阻电容模拟滤波器到复杂的数字集成电路滤波器,在高新电子产品以及智能化仪器仪表中,到处可见其活跃的身姿。MAX293/294/297是美国MAXIM公司推出的八阶低通椭网型、开关电容滤波器,采用输入时钟频率控制输出转角频率的方式来实现对模拟信号和数字信号的滤波。可广泛     

一种新型的跟踪低通滤波器

介绍了一种新型的跟踪低通滤波器的原理及实现方法.该跟踪低通滤波器用八阶椭圆型开关电容滤波器MAX293构成低通滤波电路,输入信号的频率通过单片机的测量、修正、倍频处理后输出作为MAX293的时钟控制频率,用以控制MAX293的截止频率从而实现跟踪滤波.实验证明,对于0.1 Hz～25 kHz的信号,跟踪低通滤波器的截止频率相对误差小于1%.     

一种Butterworth带通滤波器的设计与实现

提出一种基于MAX260的Butterworth带通滤波器设计方法.介绍了设计Butterworth滤波器的基本原理,以及利用MAX260实现该种滤波方式的具体过程.在实验室环境下举出具体实例实现了四阶Butterworth带通滤波器,并验证了其滤波性能.测试结果表明该方法具有较好的滤波效果.由于该方法中信号滤波由有源程控滤波器芯片完成,可降低微控制器的运算负担,有利于提升系统性能.     

视频滤波器设计

本文介绍用于视频产品的抗混叠滤波器和视频重建滤波器的设计.     

DDC中的抽取滤波器设计及FPGA实现

本文介绍了在数字下变频（DDC）中的抽取滤波器系统设计方法和具体实现方案。采用CIC滤波器、HB滤波器、FIR滤波器三级级联的方式来降低采样率。通过实际验证，证明了设计的可行性。     

Design of two-dimensional directional filters

A directional filter has a passband extending fully along a straight line passing through the origin. In its original form the transformation technique, a powerful tool for designing two-dimensional FIR filters, is not useful to design such a filter. In this communication we suggest a few analytical and optimisation-based methods to design directional filters using the transformation technique. The superiority of the proposed methods over existing techniques is demonstrated.     

一种基于CIC滤波器的有效锐化方法研究

介绍了对积分梳状滤波器（CIC滤波器）的有效锐化。所提出的锐化滤波器的结构由两个主要部分组成：一个梳状滤波器的级联部分和一个锐化滤波器部分。所提出的方案使得滤波器中锐化部分的工作速率比输入速率大为降低，其频谱响应特性比传统的也有所改进。通过MATLAB仿真，可看出改进锐化后的滤波器性能更优。     

Inverse Ultraspherical Filters

The inverse ultraspherical filter is derived and its properties analyzed. It is shown that the inverse ultraspherical filter has smaller transition band than the inverse Chebyshev filter under certain circumstances while still maintaining the maximally flat passband characteristic. Filter pole and zero calculations are described and typical magnitude and delay responses generated. Nomographs of inverse ultraspherical filters are also provided for determining filter order and for possible magnitude response optimization.Celestino A. Corral was born in Havana, Cuba. He earned his Bachelors, Masters and Ph.D. degrees in electrical engineering from the University of Miami, Florida, in 1985, 1987, and 1993, respectively. He completed his Ph.D. program under a Patricia Roberts Harris fellowship. From 1988 to 1990 Dr. Corral was a Member of the Technical Staff at Sandia National Laboratories, Albuquerque, New Mexico, where he was involved in the analysis, modeling, and design of custom circuits for piezoelectric sensor components. In 1994, he joined Scientific-Atlanta in Atlanta, Georgia, as an Associate Staff RF Engineer and worked on communication systems and specialized microwave software. In 1997 he was Senior Design Engineer at Origin Data Systems in Boca Raton, Florida, where he had multiple roles in system, hardware, and software development for a novel asset management/RFID system. Currently, Dr. Corral is a Distinguished Member of the Technical Staff in Motorola Labs, Plantation, Florida, and is involved in ultra-wideband, wideband, and propagation research. His interests include circuit and filter theory, communication systems, numerical analysis, signal processing, and constrained optimization. He has published over twenty-five journal and conference papers, has six patents filed, and two trade secrets.Dr. Corral was principal recipient of the Myril B. Reed Best Paper Award for the 40th Midwest Symposium on Circuits and Systems in 1997. Dr. Corral is also the principal recipient of the Ambrose Fleming Premium for IEE Proceedings on Circuits, Devices, and Systems, 2000. Dr. Corral is a Senior Member of IEEE and a member of Omicron Delta Kappa, Tau Beta Pi, and Eta Kappa Nu honor societies.     

波导带通滤波器的精确设计和快速优化

介绍了采用三维微波电磁场仿真软件快速提取直接耦合波导带通滤波器耦合窗口参数的方法,并提出了优化最终模型的快速扫描技术.全波仿真及实验结果表明,该方法能满足波导带通滤波器快速精确设计的要求.     

Current-mode continuous-time filters using complementary current mirror pairs

A design of current-mode continuous-time filters for low voltage and high frequency applications using complementary bipolar current mirror pairs is presented. The proposed current-mode filters consist of simple bipolar current mirrors and capacitors and are quite suitable for monolithic integration. Since the filters are based on the integrator type of realization, the proposed method can be used for a wide range of applications. The frequency of the filters can easily be changed by the DC controlling current. A fifth-order Butterworth and a third-order leapfrog filter with tunable cutoff frequencies from 20 MHz to 100 MHz are designed as examples and simulated by SPICE using standard bipolar parameters.     

大功率谐波吸收式滤波器设计

介绍了大功率谐波吸收式滤波器的实现电路，这些电路满足了信号分流的技术要求。文中给出了详细的工作原理和测试数据。     

二维自适应排序滤波器及其实时实现的几点考虑

本文首先提出了二维自适应排序滤波器２ＤＡＲＯＦ（ＴｗｏＤｉｍｅｎｓｉｏｎａｌＡｄａｐｔｉｖｅＲａｎｋＯｒ－ｄｅｒＦｉｌｔｅｒ）的结构和算法，然后分析了收敛系数和不同扫描方式在图像处理应用中对收敛和滤波性能的影响。考虑到实时处理的需要，本文还讨论了在实时实现时的几点考虑。最后，给出了２ＤＡＲＯＦ在图像去噪和恢复中的应用实例。     

Miniaturized dielectric waveguide filters

Design techniques for a new class of integrated monolithic high-permittivity ceramic waveguide filters are presented. These filters enable a size reduction of 50% compared to air-filled transverse electromagnetic filters with the same unloaded Q-factor. Designs for Chebyshev and asymmetric generalised Chebyshev filter and a diplexer are presented with experimental results for an 1800 MHz Chebyshev filter and a 1700 MHz generalised Chebyshev filter showing excellent agreement with theory.     

助听器芯片中的采样率变换数字滤波器设计

分析了助听器芯片中Σ-Δ ADC的降采样滤波器、上采样滤波器的原理及实现技术。优化滤波器结构和滤波器系数,降低了芯片面积。采用可编程配置的滤波器系数,实现通带平坦度与过渡带带宽、采样率之间的动态切换。采用SMIC 130 nm 1P8M CMOS工艺进行了MPW流片验证。结果表明,该滤波器可支持16 kHz、32 kHz采样率,满足不同采样率助听器DSP的需求。级联后滤波器的通带纹波为0.001 dB,阻带衰减达80 dB,群延时之和最大值为3.877 ms,满足助听器信号转换电路的要求。