Allpass filter using reflection coefficient of lossless networks

An approach to the design of analogue allpass filters and phase shift networks is presented which leads to designs which are more readily realised in practical circuits than by using the usual approach of using bridged T or lattice networks     

Allpass filter employing one grounded capacitor and one active element

A simple first-order current-mode allpass filter employing a Z-copy current inverter transconductance amplifier (ZC-CITA) and one grounded capacitor is presented. The natural frequency of the filter can be simply controlled by the transconductance of the CITA. On-chip experiments confirm the design assumptions.     

2-D symmetry: theory and filter design applications

In this comprehensive review article, we present the theory of symmetry in two-dimensional (2-D) filter functions and in 2-D Fourier transforms. It is shown that when a filter frequency response possesses symmetry, the realization problem becomes relatively simple. Further, when the frequency response has no symmetry, there is a technique to decompose that frequency response into components each of which has the desired symmetry. This again reduces the complexity of two-dimensional filter design. A number of filter design examples are illustrated.     

General IIR optical filter design for WDM applications usingall-pass filters

A general design algorithm is presented for infinite impulse response (IIR) bandpass and arbitrary magnitude response filters that use optical all-pass filters as building blocks. Examples are given for an IIR multichannel frequency selector, an amplifier gain equalizer, a linear square-magnitude response, and a multi-level response. Major advantages are the efficiency of the IIR filter compared to finite impulse response (FIR) filters, the simplicity of the optical architecture, and its tolerance for loss. A reduced set of unique operating states is discussed for implementing a reconfigurable multichannel selection filter     

RoF中AWG周期滤波特性应用的Optisystem设计

采用光通信仿真软件Optisystem,对基于阵列波导光栅(AWG)周期滤波特性的RoF系统用复用器和解复用器进行了仿真设计,表明基于单一AWG可实现无线(或混合)宽带RoF系统的复用和(或)解复用功能.     

Microwave Allpass Networks--Part I

In this paper it is shown that any arbitrary delay characteristic of a commensurate microwave network, which supports a TEM mode of propagation, may be realized by means of a transformerless, coupled-line network within an arbitrary additive constant. The realization procedure presented is based upon the synthesis of microwave C-type and D-type allpass sections.     

Microwave Allpass Networks--Part II

In this paper synthesis procedures are developed for the direct realization of a complete microwave allpass network without the reduction of the network to cascades of C- and D-type sections which include interdigital line structures. The application of microwave allpass networks to the phase correction of conventional microwave filters and to the construction of delay networks with linear delay characteristics is also presented.     

The design of low voltage/power current-mode sinh-domain filter for biomedical applications

This paper proposes low voltage/power, current-mode second-order Butterworth high-pass filter design in the sinh-domain for biomedical applications. The proposed filter is a continuous-time filter in the companding-class. Sinh-domain filters have the advantages of electronically adjusting the frequency response without the need for non-chip capacitors and full integration on the chip, providing low power consumption and offering a high dynamic range. These advantages of the sinh-domain are beneficial for biomedical applications due to its low power consumption requirement. The proposed filter topology is suitable for eliminating low-frequency interferences of biomedical signals like electrocardiogram (ECG), electroencephalogram (EEG), and electromyogram (EMG). In the realization of this filter, the method of simulation of passive elements with sinh-domain cells is used. The proposed high-pass filter in the 0.05 Hz-20 Hz operating frequency range with a 0.5 V power supply shows the power dissipation of 12.5 nW while its dynamic range exceeds 60 dB. Additionally, no resistances are used in the proposed topology. Simulations have been performed by using OrCAD Capture CIS to demonstrate the performance of the filter. These simulations have been implemented with the TSMC 0.25 µm CMOS process parameters.

     

Complex notch filter design using allpass filter

Complex coefficient IIR notch filter design problems are investigated. The specification of a notch filter is first transformed into that of an allpass filter. An effective approach to the design of this desired allpass filter is developed. The realisation of the proposed notch filter is equivalent to the realisation of an allpass filter. Owing to the mirror-image symmetry relation between the numerator and denominator polynomials of allpass filters, the notch filter can be realised by a computationally efficient lattice structure with very low sensitivity     

Computer aided design for new microwave filter topologies for spatial applications in Ka band

This paper presents, in the first part, an original topologie of dielectric resonators for multilayer filter applications in Ka band. The resonant element is defined by a partially metallized dielectric plate enclosed in a parallelepipedic cavity. This topology allows a high integration in a planar environment type and presents high electrical performances too. It is easily manufactured, and suitable for high frequencies filtering and power applications. In order to realize multipole filters without tuning, a direct electromagnetic optimization method developed in our laboratory is applied. This method combines a electromagnetic software based on the finite element method, and a specific one to establish the identified coupling matrix deducted from the filter responses. Some experiments are performed to verify the theoretical design. In the second part, we consider a new global function which combines filtering and radiating characteristics. For the first time, an opened tuning less two-pole filter defined by two superposed resonators coupled by a metallic iris is designed. Its filtering and radiating functions are optimized in the same time to present required electrical performances.     

Allpass networks using Wien's bridge

A general circuit configuration is developed from Wien's bridge which includes two previously described allpass filters. The rate at which the phase changes with frequency may be widely varied. One version has a transfer function whose magnitude is unity for all frequencies and rates of change of phase.     

Linear matrix inequality formulation of spectral mask constraints with applications to FIR filter design

The design of a finite impulse response (FIR) filter often involves a spectral "mask" that the magnitude spectrum must satisfy. The mask specifies upper and lower bounds at each frequency and, hence, yields an infinite number of constraints. In current practice, spectral masks are often approximated by discretization, but in this paper, we derive a result that allows us to precisely enforce piecewise constant and piecewise trigonometric polynomial masks in a finite and convex manner via linear matrix inequalities. While this result is theoretically satisfying in that it allows us to avoid the heuristic approximations involved in discretization techniques, it is also of practical interest because it generates competitive design algorithms (based on interior point methods) for a diverse class of FIR filtering and narrowband beamforming problems. The examples we provide include the design of standard linear and nonlinear phase FIR filters, robust "chip" waveforms for wireless communications, and narrowband beamformers for linear antenna arrays. Our main result also provides a contribution to system theory, as it is an extension of the well-known positive-real and bounded-real lemmas.     

DXCCII-based grounded inductance simulators and filter applications

In this paper two new grounded inductance simulators based on DXCCII suitable for operation in 30 kHz-30 MHz frequency range, are presented. The proposed circuits both employ only a single dual X second-generation current conveyor (DXCCII) active device accompanied with three and four passive elements, respectively. The accuracy of the simulated inductors is verified by implementing them in some filter applications. Also, a novel multi-input single-output universal filter derived from one of the new grounded inductance simulators is simulated to demonstrate the functionality of the proposed circuit. Simulation results using AMS 0.35 μm CMOS process technology parameters are included.     

On the Realization of MOS-Only Allpass Filters

The objective of this paper is to present a simple filter topology, which can be used to implement first- and second-order MOS-only allpass filters. The resulting filters realize the allpass functions without using any external passive components; hence these occupy very small chip area and are capable of operating at high frequencies. Cadence Spectre simulation and experimental results verifying the main advantages of the filters are provided.     

New linear-programming-based filter design

It is well known that the filter-design problem with mask constraints can be formulated as a semi-infinite program. There are two approaches toward the solution of this semi-infinite program. The first griding approach relaxes the semi-infinite constraint by refining it in the finite griding domain so it does not always guarantee global optimal and feasible solution. The second semi-definite programming (SDP)-based approach does guarantee the global optimal solution and excellently handles positive real constraints. However, the magnitude constraints are still persistent and not yet handled by SDP tool in an efficient manner. In this brief, a new tight polyhedral approximation for semi-infinite constrained domain is proposed. Based on it, we present a new linear-programming-based solution method for filter design, which unlike the griding approach yields global solution and unlike SDP based approach is practical for even long-tap filters. Simulation results confirm the viability of the proposed method.     

Rapid Cauer filter design employing new filter model

The exact three-dimensional (3D) design of a coaxial Cauer filter employing a new filter model, a 3D field simulator and a circuit simulator, is demonstrated. Only a few iterations between the field simulator and the circuit simulator are necessary to meet a given specification     

Double-split-electrode transversal filter for telecommunication applications

A novel structure for on chip tap weight implementation in CCD transversal filters is described which employs two splits in the CCD sensing electrodes to improve on the performance of the conventional single-split weighting technique. This greatly reduces the capacitance associated with the sensing nodes and consequently reduces the common mode signal, gain sensitivity, coefficient error, and clock noise pickup. Experimental results are presented which verify this improved performance. The results achieved for a 3.4-kHz low-pass filter clocked at 32 kHz show a signal-to-noise ratio of 86 dB with harmonic distortion of less than 0.3 percent.     

Selectivity-improved E-plane filter for millimetre-wave applications

Measurements on a Ka-band selectivity-improved E-plane filter prototype are compared with computed predictions and are found to be in excellent agreement. The measured insertion loss is 1.5 dB, and the bandwidth is 180 MHz centred at 32.8 GHz. These prototype measurements confirm that this design has the potential for significantly improving the performance of filter components in the millimetre-wave frequency range.<>     

新型异向介质及其在滤波器中的应用

提出了一种结构简单、损耗小、阻带宽的新型异向介质单元.在对该异向介质单元进行等效电路分析的基础上,研究了其结构参数对电磁波传输的影响,并利用S-参数提取法对其等效磁导率和介电常数进行了提取,揭示了该异向介质单元的带阻工作原理并进一步验证了其等效电路和分析的合理性.采用该异向介质单元设计出的截止频率为9.6 GHz的波导...