Polarization-independent all-fiber flat-top comb filter

A novel polarization-independent all-fiber flat-top comb filter based on high birefringent (Hi–Bi) fiber Sagnac interferometer is proposed for the first time to our knowledge. The numerical simulation results show that the proposed device exhibits flat-top and the extinction ratio reads about 30 dB. A good agreement between the numerical simulations and the experimental results is achieved.     

Tunable high-Q surface-wave comb filter

Comb filters with tunable passband characteristics have been achieved using a muItitap surface-wave delay line with electronic phase-shifting circuits in the feedback loop. The results are obtained either by summing the acoustic signals on the substrate or by using electronic summers. Q's ranging from 500 to 50 000 have been measured for the surface-wave comb filters.     

以ⅡR滤波器作补偿的CIC滤波器设计

为解决积分梳状(CIC)滤波器通带失真大和阻带衰减小对其应用的限制,在分析传统CIC滤波器幅频特性的基础上,给出一种用二阶ⅡR滤波器作为补偿滤波器级联CIC滤波器的改进方法。仿真结果表明,它与同级数规模的内插二阶多项式CIC滤波器、锐化CIC滤波器(SCIC)相比,通带和阻带的性能得到较大改善,实现复杂度较低。因此,它适用于对通带、阻带性能和实现复杂度要求较高的多采样率转换系统。     

Low power analog comb filter for biomedical applications

An analog topology is proposed to implement a comb filter for removal of power-line interference from various low-amplitude biomedical signals. In this proposed methodology, an n-number of all-pass filters (APFs) and an adder circuit are used to suppress n-number of frequencies. All the APFs as well as the adder circuit are designed using a current conveyor to utilize the various properties of the current-mode circuits. The active and passive components used to design the comb filter include second-generation current conveyor (CCII±), resistor, and capacitor. The circuit is designed for n?=?4 to remove the power-line frequency of 50 Hz, and its three odd harmonics such as 150 Hz, 250 Hz, and 350 Hz. A PSPICE simulation is done to verify the performance of the proposed circuit. In simulation, all CCII±?are designed using macro model of commercially-available current feedback operational amplifier integrated circuit (IC) AD844 as well as dynamic threshold voltage metal oxide semiconductor technology. The proposed circuit is also implemented also using commercially available IC AD844 on breadboard for n?=?3. The output result on digital storage oscilloscope confirm the effectiveness of the proposed comb filter circuit in removing the power line interference i.e. the power-line frequency and its odd harmonics.     

Computation of even-order elliptic filter functions

An extension of Darlington's algorithm to obtain elliptic odd-order transfer functions is presented which can be used to obtain even-order class A elliptic transfer functions.     

一种基于采样布拉格光栅的梳状滤波器解决方案

基于采样布拉格光纤光栅,设计出一种多通道数梳状滤波器,所设计的梳状滤波器可应用于光纤通信中的波分复用（WDM）系统。在光栅中引入一种非连续线性啁啾阶梯式结构,并且在采样内,使折射率调制深度符合汉明分布,设计出一个具有26个通道、通道间隔25GHz的梳状滤波器,它能够产生具有平顶、陡峭边沿以及高透射率的多个相同的通带,可用作多通道光分插复用器,广泛应用于WDM系统。     

Novel droop-compensated comb decimation filter with improved alias rejections

This paper presents a novel two-stage comb decimator with the improved magnitude characteristic. Simple multiplierless corrector filters, which are designed using the frequency sampling and IFIR methods, are introduced. The proposed filters compensate the comb passband droop in the wideband passband region and increase the attenuations in the folding bands. Using the multirate identity the filters may be moved to a lower rate. The filter design depends only on the number of the cascaded comb filters and do not depend on the decimation factor M.     

新型梳状滤波器Y/C分离电路

介绍了当前彩色电视亮／色分离技术中2种动态梳状滤波器的电路结构与特点，并给出了较详实的应用技术参数。     

Narrowband bandpass filter exhibiting harmonic suppression

A novel bandpass filter is presented using ring resonators employing corrugated couplers in order to provide suppression of the second harmonic. The filter exhibits a 2.0% bandwidth at a centre frequency of 2.604 GHz and provides a 39 dB suppression of the second harmonic. The constituent resonator is described and an analogous bandpass filter without corrugations is presented for comparison.     

级联积分梳状滤波器与DSP的实现

级联积分梳状滤波器(CIC)在数字信号处理中有着广泛的应用,特别适合用在信号带宽为窄带的降采样、升采样的数字变频中。首先对CIC的原理与DSP实现进行分析,然后给出了不同寻址方式的存储器安排图。     

A multipurpose CCD comb filter with combing and delaying functions

Describes the organization and performance of a multipurpose CCD comb filter to separate luminance and chrominance from the composite color video signal. The filter consists of a main (long) and two sub- (short) channels terminated at two comb outputs (add and subtract) and a simple delayed output. It is operated at 4/spl times/f/SUB SC/(f/SUB SC/: color subcarrier frequency). The comb filter transfer functions are usually shifted toward the lower frequency and the rejection ratios are degraded, due to the incomplete charge transfer. However, the small notch frequency shifts (<25 Hz) and high rejection ratios (>40 dB) were experimentally obtained. Moreover, low differential gain (<1 percent) and low differential phase (<1.5/spl deg/) were obtained for the separated chrominance signal, regardless of APL variation. The second-order comb filter was constructed using three identical devices and used in a TV receiver. The reproduced image was much superior to that obtained by the conventional separation circuit. Some other application schemes in video signal processing systems were proposed.     

Compact and wide stopband lowpass filter with novel comb CMRC

A novel comb compact microstrip resonant cell, entitled CCMRC, is firstly proposed. The compact configuration presents ultra wide stopband and attractive slow-wave characteristics. A lowpass filter, consisting of three CCMRCs connected in series, is designed and fabricated. The filter has the merits of low insertion loss in the passband, sharp, deep and wide rejection in the stopband and compact size. Good agreement between experimental and simulated results is achieved.     

基于梳状滤波器的光纤甲烷传感器的研究

采用基于Sagnac的保偏光子晶体光纤(polarization-maintaining photonic crystal fiber,PM-PCF)滤波器,将宽带光源精确匹配甲烷气体在近红外波段的几个吸收线谱.设计出一个简单合理的多反射气室,使得光源和甲烷气体之间能够充分相互作用,提高了系统的灵敏度.同时,在测量甲烷气体浓度时,加入乙炔气体作为干扰,通过实验验证了该方案能够有效减缓交叉气体的灵敏度.     

基于光子晶体光纤Sagnac环梳状滤波器的设计

提出了由两段高双折射光子晶体光纤构成的Sagnac环滤波器,利用Jones矩阵理论对所提出的Sagnac环滤波器的传输函数进行了理论推导,并分析了光子晶体光纤双折射大小、两段光子晶体光纤的长度,以及偏振控制器的偏转角度对滤波器透射光谱特性的影响,并以此为基础设计出平顶梳状交错滤波器。此类滤波器在密集波分复用系统中有着广阔的应用前景。     

Miniaturized dual-mode bandpass filter with harmonic control

This letter presents a miniaturized dual-mode microstrip bandpass filter with the right crossed slots. The right crossed slots perturb and reduce the fundamental resonant frequency, but the second resonance is not affected. Therefore, the second resonance will be effectively higher than 2f/sub o/, where f/sub o/ is the fundamental frequency. Since the fundamental frequency is lower, the bandpass filter is smaller than the conventional filter. The proposed filter shows a 4.4% fractional bandwidth at 1.595GHz with a return loss of better than 10dB and an insertion loss of less than 2.5dB, while the second passband is located around 2.88f/sub o/= 4.6GHz. Compared with the conventional square patch filter, the proposed filter also shows a 58% size reduction.     

圆谐梅林滤波器在模式识别中的计算机仿真研究

为了实现滤波旋转和尺度不变的目的,提出了将圆谐梅林滤波器用于模式识别。从圆谐展开函数引出旋转不变滤波器,从梅林变换引出尺度不变滤波器,并将这两个滤波器结合得到旋转和尺度不变的圆谐梅林滤波器。计算机模拟实验证明,圆谐梅林滤波器具有旋转和尺度不变性;能很好地提取畸变物体的角点和边缘,尤其是角点,并可以由角点处的相关输出峰值判断边的结构。     

基于谐波频谱的LCL滤波器性能分析

为了减少逆变器中的谐波干扰,常采用LCL滤波器,该滤波器性能优良,被广泛采用,但目前LCL滤波器的电感电容仍然较大,系统成本仍较高,据此提出一种新型的设计方法,即通过逆变器输出的高次谐波峰值及其频谱,采用直线交截法依次获得谐振频率等相关滤波参数。与此同时,在此基础上对基于谐波频谱的LCL滤波器的各参数再次进行优化,然后通过与未经优化的LCL滤波器进行性能分析比较,从理论上揭示了该滤波器的优越性。最后通过在三相并网逆变器上进行实验验证,最终设计出了总电感电容较小,且满足并网要求的LCL滤波器。     

Design of high-temperature superconducting low-pass filter forbroad-band harmonic rejection

A new type of low-pass filter based on a coupled line and transmission line theory is proposed for suppressing harmonics and spurious frequency. The seventh-order coupled-line low-pass filter with strip line configuration was fabricated using a high-temperature superconducting (HTS) thin film on MgO(100) substrate. The seventh-order low-pass filter has five attenuation poles in the stop band. Its cutoff frequency is 1 GHz with a 0.01-dB ripple level. The fabricated filter exhibits a characteristic stop band in the range from 1 to 7 GHz. A measured insertion loss at the pass-band of the HTS low-pass filter is 0.2 dB at 77 K, while the maximum return loss is 17.1 dB. These results match well with those obtained by the EM simulation. The new low-pass filter structure is shown to have attractive properties such as compact size, wide stop band range, and low insertion loss     

A monolithic analog video comb filter in 1.2-μm CMOS

A fully integrated comb filter for luminance/chrominance (Y/C) separation of NTSC video signals is fabricated using a standard 1.2-μm double-poly CMOS technology. This paper demonstrates its use of analog RAM structures in the realization of video line delays. Information is stored and retrieved using switched-capacitor techniques optimized for operation in a parasitic dominated environment. Fixed pattern noise is avoided through the use of serial data paths whenever possible, necessitating the use of a G_m-enhanced amplifier and techniques to improve the feedback factor. The 11.7 mm² adjustment-free circuit, which requires a single clock and reference current, dissipates 170 mW at 5 V and yields an SNR of 51 dB and frequency response flat within 1.1 dB to 4.2 MHz     

多次谐波抑制的微波滤波器

提出一种新型的具有多次谐波抑制功能的发夹型微波带通滤波器,主要工作在2GHz频率。对该滤波器通过仿真优化,并进行实际设计测量。在该结构滤波器中,采用阶跃阻抗结构的发夹谐振器来达到缩小尺寸、多次谐波的目的。该滤波器相比于传统的微带线发夹型滤波器具有尺寸小,频率选择性好,阻带宽的特点。