自动线性跟踪Butterworth有源滤波器研究

滤波是通信、测试、数据采集和实时控制等领域至关重要的环节。通常的模拟滤波器，由于截止频率固定，在某些宽频率动态范围且有实时性要求的应用场合，往往达不到预期的滤波效果，有时甚至影响整个系统的正常运行。本文从有源滤波器的机理分析入手，提出了一种由单片机参与的滤波系统，它能自动跟踪输入信号频率，线性地选择合适的滤波器截止频率，弥补了原有滤波器的不足。     

Indirect test of M-S circuits using multiple specification band guarding

Testing analog and mixed-signal circuits is a costly task due to the required test time targets and high end technical resources. Indirect testing methods partially address these issues providing an efficient solution using easy to measure CUT information that correlates with circuit performances. In this work, a multiple specification band guarding technique is proposed as a method to achieve a test target of misclassified circuits. The acceptance/rejection test regions are encoded using octrees in the measurement space, where the band guarding factors precisely tune the test decision boundary according to the required test yield targets. The generated octree data structure serves to cluster the forthcoming circuits in the production testing phase by solely relying on indirect measurements. The combined use of octree based encoding and multiple specification band guarding makes the testing procedure fast, efficient and highly tunable. The proposed band guarding methodology has been applied to test a band-pass Butterworth filter under parametric variations. Promising simulation results are reported showing remarkable improvements when the multiple specification band guarding criterion is used.     

基于ADS的滤波器类型选择对滤波性能的影响分析

基于ADS设计滤波器一般设计方法,提出了滤波器设计过程中类型选择对器性能有一定的影响,利用ADS滤波器设计向导,进行3种不同类型滤波器的仿真,得到在滤波器的幅频特性和群延时上,给出仿真结果,并且对仿真结果进行对比分析,综合比较得出3种类型滤波器性能的优劣,为之后滤波器的设计给出一个指导方向,具有一定的理论意义。     

基于红外背景复杂程度描述的小目标检测算法

提出了关于红外“背景复杂程度”的基本概念,发现并论述了一种有效的红外背景复杂程度定量描述方法。此外,提出了一种基于红外背景复杂程度描述的自适应Butterworth高通滤波方法,实现了具备一定普适性的红外图像预处理。在小目标检测问题的研究中,构造并实现了一种更具实用性的先检测后跟踪小目标检测算法,此算法在一个完整的框架下实现了红外图像预处理过程和小目标检测过程的自适应统一。     

Butterworth Window for Power Spectral Density Estimation

The power spectral density of a signal can be estimated most accurately by using a window with a narrow bandwidth and large sidelobe attenuation. Conventional windows generally control these characteristics by only one parameter, so there is a trade-off problem: if the bandwidth is reduced, the sidelobe attenuation is also reduced. To overcome this problem, we propose using a Butterworth window with two control parameters for power spectral density estimation and analyze its characteristics. Simulation results demonstrate that the sidelobe attenuation and the 3 dB bandwidth can be controlled independently. Thus, the trade-off problem between resolution and spectral leakage in the estimated power spectral density can be overcome.     

Analog active filter design using a multi objective genetic algorithm

The selection of the correct values for passive elements, resistors, and capacitors, is an important task in analog active filter design. The classic method of choosing passive elements is a difficult task and can lead to errors. To reduce the incidence of error and human effort evolutionary optimization techniques are used to select the values of capacitors and resistors. However, due to the single objective optimization technique, these are not well suited to optimize different filter parameters. For this reason, the performance of a multi-objective genetic algorithm named non-dominated sorting genetic algorithm II (NSGA-II) against the different single objective algorithms is evaluated. Two analog active filters: A fourth order Butterworth and a second order state variable filter with the operational amplifiers in their cores are used for testing purposes. In both cases two different objects are chosen along with eight components as variables to be optimized. The component values are compatible with the E12, E24 and E96 series using NSGA-II. The computation results are better in terms of design error and allow for better resistor and capacitor choice. To reach the same or better results the NSGA-II needs fewer generations compared with other genetic algorithms for this problem.     

基于巴特沃斯逼近的二维IIR数字滤波器的设计

本文给出了一种基于巴特沃斯逼近的二维ＩＩＲ数字滤波器的设计方法，得到了由基本的全通节级联，并联实现的各种二维滤波器函数，包括，镜象对称互补滤波器，扇形滤波器和具有任意矩形通、阻带的滤波器，结果表明，这种实现结构具有通有灵敏度低、滤波器系数少的优点，并且由于巴特沃斯逼近的最大平坦性，得到的滤波器具有良好的相位特性。     

Continuous-Time 4th Order Butterworth Low-Pass Filter for Video Frequency Applications

In this paper, a continuous-time 4th order Butterworth low-pass filter based on current-mode processing is presented for applications over the video frequency range. A new type of integrator in which both voltage and currents may be integrated is presented and used as the main active block. The filter has been implemented using a very low-cost 2.4 m CMOS process (Mietec). The whole circuit occupies 2.8 mm² and consumes 19 mW from a ±1.5 V supply. Experimental results are given for a 4.5 MHz to 12 MHz tunable low-pass filter with 58 dB of dynamic range at 10 MHz.     

基于Matlab的模拟滤波器设计与仿真

巴特沃思、切比雪夫模拟低通滤波器通常是设计模拟高通、带通和带阻滤波器的原型,先按给定频率响应巴特沃思、切比雪夫低通Ha（s）逼近,然后由选定Ha（s）实现二端口网络的电路结构和参数值。在此对达林顿T型和П型电路结构的滤波器元件参数进行了编程计算,并对其系统函数的幅频特性进行仿真。仿真结果符合设计要求,该方法便捷,程序具有可扩展性。     

二阶压控电压源低通滤波器设计

本文详细介绍二阶压控电压源低通滤波器的设计方法,给出了其通用表达式。设计方法是根据所需转折频率,在1:2至1:10较宽的范围内灵活取两电容值,再计算出与灵活选取的电容准确匹配的电阻阻值。相对于查表法、图示法取值更具灵活性和实用性,由于不需要精确匹配成本较高的电容,此方法还具有成本较低的优势。用Multisim-10仿真软件对所设计的二阶压控电压源低通滤波器进行模拟仿真,结果表明与理论计算符合得很好。