高阶带通滤波器设计研究

本文详细讨论了FIR线性相位滤汉器幅频特性与神经网络算法之间的关系,证明了神经网络的收敛性条件,给出了FIR高阶带通滤波器的设计实例,研究结果表明该算法在高阶带通滤波器的优化设计中的有效性和优异性能。     

Novel first-order differential class-AB log-domain allpass filters

The first-order differential class-AB log-domain filters are proposed. They are systematically derived using the state–space synthesis procedure. It is also demonstrated that the present second filter cannot be realized without using differential class-AB type. To the best knowledge of the authors, the filters are the first log-domain first-order allpass filters in the literature. PSPICE simulations are performed using both, bipolar junction transistors (BJT) and ideal devices to confirm the theoretical analysis. Tolerable differences are observed due to BJT non-idealities such as finite-beta, non-zero ohmic junction resistances and early voltages.     

Novel single-stage second-order structure for low-pass wide-band low-power continuous-time filters

A novel single-stage second-order structure for Gm-C filters is presented. It allows ample reduction in hardware and thus power consumption. Moreover, due to exploiting otherwise parasitic poles, the structure allows much higher bandwidth than in conventional designs, be achieved. To verify effectiveness of new concept, and based on the new approach to implement second-order stages, a third-order and a fifth-order continuous-time low-pass filters were implemented. The filters fabricated in a CMOS process, achieved more than 430 MHz, bandwidth and less than THD for a 400 mV_p–p 100 MHz input signal. All these accomplished with a factor of about four reduction in hardware and power. The bandwidth, output voltage swing, and dynamic range are far larger than those of any other CMOS low-pass filters thus far reported, which have bandwidth higher than 100 MHz.     

一种对数域电流模式积分器及其在高频滤波中的应用

提出了一种新颖的对数城电流模式积分器。该积分器的时间常数由参考偏置电流控制。用该积分器设计了二阶带通滤波器和0．1dB纹波三阶Chebyshev低通滤波器。计算机仿真表明，所设计的滤波器实际频响特性几乎是理想的，而且高频谐波失真很小，通频带灵敏度很低，频率在很宽的范围内可控。电路由双极型晶体管和接地电容构成，适合于全集成实现。     

Realization of band-pass and low-pass filters on a single chip in terahertz regime

In this paper, we present the design, simulation, fabrication and characterization of a terahertz(THz) filter based on metamaterial consisting of the periodical double symmetric splits ring resonator(DS-SRR) array. We can observe that the metamaterial-based filter possesses a band-pass transmission when the electrical field is along y direction, and it possesses a low-pass transmission when the electrical field is along x direction. Our results demonstrate that the proposed filter can realize the switching between band-pass effect and low-pass effect by only changing the polarization direction of the incident electromagnetic wave. Moreover, the calculated surface current distributions are also used to analyze the switchable mechanism of the THz metamatrial filter. Therefore, the proposed THz wave filter has a potential application in THz wave communication systems.     

一维光子晶体异质结结构偏振带通滤波器

利用一维光子晶体(PC)异质结结构带边峰值叠加的方法设计了一种偏振带通滤波器,在实现p偏振分量带通滤波的同时实现了禁带范同的展宽.给出了设计方法,讨论了这种带通滤波器的通带特性和禁带特性.所设计的偏振带通滤波器具有宽通带、宽禁带、膜层较少、小型化和类矩形通带等特点,制作简单,具有实际应用价值.     

Realization of current-mode high-order filters employing multiple output OTAs

Current-mode linear transformation (CMLT) high-order filters with minimum number of multiple output operational transconductance amplifiers (MOOTAs) are presented. Based on proposed design methods, we can synthesize current-mode high-order all-pole filters with minimum number of MOOTAs and all grounded capacitors efficiently. Moreover, high-frequency canonical CMLT elliptic filters with minimum number of MOOTAs and floating capacitors are also presented. Our proposed filters have the following merits: simplified design procedures, minimum number of active elements and simple design equations. Two design examples are demonstrated in this paper. Experimental results that confirm the theoretical analysis are provided.     

改进型跳耦结构电流镜滤波器

提出了一种利用电流镜积分器和微分器实现的改进型跳耦结构滤波器,讨论并比较了跳耦结构和改进型跳耦结构滤波器的设计方法,改进方法突破了单纯用电流镜积分器实现滤波器的局限,简化了椭圆函数滤波器的信号流图和电路结构;完成了MOS级的计算机仿真,仿真结果表明所提出的电路方案正确有效。     

Voltage-mode high-Q band-pass filters and oscillators employing single CDBA and minimum number of components

In this paper, voltage-mode second order high-Q band pass filters and oscillators which employ only single current differencing buffered amplifier (CDBA) as the active component are proposed. One of the four filter circuits and two of the four oscillators described have minimum passive component count properties, without using the internal pole of the active element. These BP filters can be easily cascaded without any recourse to impedance matching circuitry. The circuits have been analysed theoretically, simulated and experimentally tested in a laboratory. It is shown that the results of simulations and experimental work are in agreement with theoretical predictions.     

All-inkjet-printed low-pass filters with adjustable cutoff frequency consisting of resistors,inductors and transistors for sensor applications

Low-cost and flexible first and second order low-pass filters with adjustable cutoff frequency were designed and printed by inkjet printing technology. The all-inkjet-printed low-pass filters were characterized and an adjustable cutoff frequency feature in form of an inkjet-printed organic thin-film transistors (OTFTs) was added to the filters for application-oriented fine-tuning. The applicability of these small circuits was evaluated by signal filtering for sensor applications. As a result, low-pass filters with an adjustable cutoff frequency ranging from 82 Hz to 740 Hz were obtained, demonstrating their suitability in signal filtering and their promising applicability for tactile sensing characterized by low frequency signals.     

一种高阶低通FIR滤波器的Matlab与FPGA实现

滤波器是电子专业常用的信号处理工具,是用来减少或消除干扰的电气部件。文章基于FPGA开发的自顶向下层次化的设计思路,采用Matlab以及QuartusⅡ软件设计实现16阶低通滤波器,仿真以及实物测试结果都显示达到低通滤波性能。与传统的数字滤波器相比,FPGA器件更优越的性能使得所设计的滤波器具有更好的实时性、可移植性等。     

Universal filters of arbitrary order and type employing square-root-domain technique

Novel Single Input Multiple Output (SIMO) and Multiple Input Single Output (MISO) universal filter topologies of arbitrary order and type are introduced in this paper. The proposed topologies have been realised by employing Square-Root Domain (SRD) technique. An offered benefit of the universal filter topologies is that only grounded capacitors are required for their implementations and the resonant frequency of the filters can be electronically controlled by an appropriate dc current. The proposed universal filters simultaneously offer all the five standard filtering functions i.e. Lowpass (LP), Highpass (HP) and Bandpass (BP), Bandstop (BS) and Allpass (AP) frequency responses. In addition, the SIMO topology is generic in the sense that it can yield four different stable filter configurations. Two design examples are provided in each configuration and the correct operation of the corresponding topologies has been evaluated through the PSPICE software with BSIM 0.35-µm CMOS process model parameters.     

1D linear-phase band-pass multiplierless FIR Hilbert transformers and filters

An original analytical method, based on modified Christoffel–Darboux formula, is used in the paper in order to synthesise a linear-phase band-pass finite impulse response (FIR) filter function that can have an effect of Hilbert transformer. New structure of the band-pass FIR filter in recursive realisation, together with the corresponding difference equation, is presented providing the efficient filter solution without multipliers. Several examples of filter types for different parity of two real free integer parameters, including a particular solution of Hilbert transformer, are considered in terms of required number of adders and values of cut-off frequencies of the pass and stop bands. A comparison of the proposed band-pass filter characteristics with those of a classical filter solution is provided in the paper.     

Miniature and tunable millimeter-wave lowpass filter with MEMS switch

In this paper, fully monolithic tunable millimeter-wave filters with tapped-line feedings are proposed using the CPW-based periodic structures with novel multiple-contact MEMS switches. Millimeter-wave low-pass filters were designed, fabricated, and tested. The cascaded CPW-based periodic structures, with low-pass intrinsic filtering characteristics, are reconfigured into a self-similar single unit cell by the operation of the novel multiple-contact MEMS switches with single actuation. The measured results of the reconfigurable low-pass filter show the 3-dB cutoff frequency change from 19 to 11 GHz with very small change in the average insertion loss from 1.3 to 1.9 dB. The chip size of the low-pass is 4.0 mm × 1.6 mm.     

Some extremal properties of Daubechies filters and other orthonormal filters

New extremal properties of Daubechies 4-tap orthonormal filters are given: they maximize a certain functional, have the largest gain in (0,π/2), and allow maximum energy compaction in [0,π/2]. These properties do not carry over to Daubechies filters of arbitrary length. They complement what is known about Daubechies filters and highlight the specific role of the 4-tap filter. Moreover, we demonstrate that these properties cannot be fulfilled by any other orthonormal lowpass filter, regardless of its length.     

LPFG带通滤波器的芯模阻隔器设计与制作

为有效地阻挡长周期光纤光栅（LPFG）器件芯模,实现包层模提取技术,提出了利用磁流变液实现芯模阻隔（CMB）的新方法。从模式耦合理论出发,基于LPFG的单多模级联网络结构,分析了LP01模和HE13包层模与多模光纤（MMF）耦合效率随CMB器芯径的变化规律,并对CMB器尺寸进行了优化设计。根据理论分析结果,将磁流变液注...     

形貌检测频域低通滤波器及检测误差修正

文章提出了用于傅里叶变换形貌检测法的新频域低通滤波器,并提出了修正在检测大梯度变化物体时常出现跳跃误差的相位逆解调法,给出了实际测量结果,并证明其具有使用简单、参数调整方便、应用范围广等特点,尤其是对具有大梯度表面和棱角细节的物体检测更有独到之处     

Modular analysis and design of log-domain circuits based on LIN↔ELIN transformations

We systematized and developed some procedures for the modular design of externally-linear internally nonlinear (ELIN) circuits resulting in a general LIN↔ELIN transformation procedure. This one was also extended to analysis of these types of circuits. The procedure is exemplified on log-domain circuits. In the design one starts with the linear block diagram (LIN) described by transfer functions and one substitutes directly each linear building block by a corresponding nonlinear one. The parameters of each nonlinear component depend on the given parameters of its linear correspondent. Input F ⁻¹ and output F blocks are added. In the analysis one identifies the nonlinear basic circuit components and each of them is substituted by its corresponding linear building block. Input and output F ⁻¹-F cells are removed. The ideal transfer function can be calculated on the linear block diagram now. The LIN↔ELIN transformations make a direct connection between equivalent linear and ELIN circuits, simplify their design and analysis procedures and permit the development of CAD procedures.     

Coefficients of maximally flat low and high pass nonrecursive digital filters with specified cutoff frequency

A simple and general method is presented for determining the coefficients of a lowpass or highpass maximally flat nonrecursive digital filter with a specified cutoff frequency.