Cascadable allpass filter with a single DO-CCII and a grounded capacitor

In the literature sufficient emphasis has not been given to dual-output current conveyors in all-pass filter designs. In this study, a cascadable voltage-mode all-pass filter with a grounded capacitor using a single dual-output current conveyor has been reported.     

Current mode allpass/notch and bandpass filter using single CCII

A current mode second-order allpass notch and bandpass filter using a single CCII, two grounded capacitors and four resistors is proposed. The allpass and notch output current signals, taken out through port z of a CCII and having high output impedance, can be obtained by tuning a resistor in the proposed network. The resonance angular frequency and quality factor of the new network have the advantages of low passive sensitivities and are insensitive to the current tracking error of the nonideal CCII.<>     

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     

用第三代电流传送器设计n阶有源滤波器

提出了一种基于第三代电流传送器(CCIII)的电流模式n阶通用滤波器的设计方法,导出了设计公式,利用该方法可生成n阶高通、低通、带通滤波器,所产生的n阶滤波电路由n个CCIII+、2 n个无源元件构成。以二阶滤波器为例分析了高通、低通、带通滤波电路,结果显示各滤波电路的无源灵敏度和有源灵敏度都很低,以极点角频率106 ...     

Biquadratic filter sections employing a single current conveyor

LP, BP and HP filters with low passive component sensitivity and independently adjustable ?0 or Q are presented. In addition, two new types of current conveyor are introduced and a new current-conveyor classification is proposed.     

A novel first-order log-domain allpass filter

This paper proposes a first-order allpass log-domain filter, which is systematically derived using the state-space synthesis procedure. To the best knowledge of the authors, the filter is the first log-domain first-order allpass filter in the literature. The proposed filter has a simple structure and can be electronically tuned. PSPICE simulations are given to confirm the theoretical analysis.     

Efficient tunable IIR and allpass filter structures

A new recursive filter structure is proposed which can be controlled on-line using a single parameter. The structure can be used for interpolation in timing synchronisation of digital communications receivers. The technique is illustrated with an example of the implementation of a tunable fractional delay allpass filter using the Thiran design technique     

Tunable allpass filter for low voltage operation

A novel high-performance first-order allpass filter with electronically adjustable filter parameters is presented. The core of the circuit is an inverting unity gain amplifier with electronically adjustable output resistance, which leads to an allpass filter realisation with tunable time constant. The circuit is composed of a simple CMOS cascode circuit and a level shifter and is also very suitable for low voltage operation, since it employs two active devices between its rails. SPICE simulation and experimental results verifying theoretical analyses are also given.     

Dual-mode dual-band bandpass filter for single substrate configuration

A novel dual-mode dual-band bandpass filter (BPF) is proposed that uses a bi-interdigital coupling structure for a single substrate configuration. The BPF consists of a microstrip feed network, ground embedded slots, and outer and inner loop resonators which are excited over bi-interdigital coupled lines with tight coupling in the two passbands. The filter design, analysis via the equivalent circuit of the proposed BPF and the experimented results are dealt with.     

Single MIMO-OTA and single-grounded-capacitor-based first-order allpass filter design

A novel first-order voltage-mode allpass (AP) filter employing a single multiple-input-multiple-output operational-transconductance-amplifier (MIMO-OTA) and a single grounded capacitor is introduced in this article. Compared to the corresponding already published topologies, the offered benefits are as follows: it employs minimum number of active and passive components; the only capacitor is grounded, which is good for a monolithic integration of an IC; and the absence of any matching condition for its realisability. The performance of the proposed circuit has been evaluated through simulation results, utilising the analogue design environment of Cadence software.     

Interpolated LIR Mth-band filter design with allpass subfilters

We propose a new allpass-based structure for the IIR Mth-and 2Mth-band filters. These filters consist of M allpass filters and an interpolation filter (sum of two allpasses). Consequently, the proposed structure is very efficient in implementation. By choosing the allpass phase appropriately, the resulting phase response of the IIR Mth-band filter becomes approximately linear. An example is designed and compared with FIR Mth-band filters     

Tunable multiwavelength fiber laser employing a comb filter based on a polarization-diversity loop configuration

A tunable multiwavelength fiber laser based on a semiconductor optical amplifier (SOA) is newly proposed. The proposed fiber laser employs a fiber comb filter based on a polarization-diversity loop configuration (PDLC) for the multiwavelength selection. The spectral characteristic of the comb filter is graphically explained by tracing the state of polarization (SOP) of the light propagating through the filter on the Poincare sphere. Particularly, the method of adjusting the filter characteristics is established with the help of the Poincare-sphere representation. The experimental results show that 18 laser lines oscillate with the signal to amplified spontaneous emission noise ratio over 25 dB. Particularly, all of the laser lines with a fixed channel spacing of /spl sim/ 0.8 nm can be continuously shifted by adjusting only a wave plate contained within the filter.     

New complex-pole single-amplifier allpass filter with reduced active-element sensitivities

A new complex-pole allpass network is described which is based on the minimum-transmission properties of an RC parallel-T network. The proposed structure is compared with the canonic Deliyannis arrangement, and analytical and experimental evidence is presented which indicates an improved sensitivity to finite-amplifier-gain effects.     

High-output-impedance current-mode multiphase sinusoidal oscillator employing current differencing transconductance amplifier-based allpass filters

This article presents a multiphase sinusoidal oscillator using current differencing transconductance amplifier (CDTA)-based allpass filters. The oscillation condition and oscillation frequency can be orthogonally controlled. The proposed circuit provides 2n – phase signals (n≥2) that are equally spaced in phase and of equal amplitude. The circuit requires one CDTA, two resistors and one capacitor for each phase and no additional current amplifier. Owing to high-output impedances, the proposed circuit enables easy cascading in current-mode configurations. The effects of the nonidealities of the CDTA-allpass sections were also studied. The results of PSpice simulations are presented, demonstrating their consistency with theoretical assumptions.     

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     

Band-elimination filter employing surface-acoustic-wave resonators

A surface-acoustic-wave (s.a.w.) band-elimination filter has been developed employing s.a.w. resonators composed of interdigital transducers with a large number of electrodes, exhibiting more than 80 dB stopband rejection with a passband attenuation of less than 1 dB.     

Adjustable coupled two-cavity allpass filter for dispersion slopecompensation of optical fibres

The filter gives variable compensation between -2.0 and -15.5 ps ³ over a bandwidth between 3.6 and 1.2 nm, respectively. The filter performance agrees quite well with that predicted by existing theory     

Resistorless realization of current-mode first-order allpass filter using current differencing transconductance amplifiers

This paper presents a realization of a current-mode first-order allpass filter using two current differencing transconductance amplifiers (CDTAs) as the active components and one virtually grounded capacitor as the only passive component. The proposed filer requires no external resistor and is electronically adjustable by varying the external bias current of the CDTA. No component-matching constraints are required. The circuit realizes both inverting and non-inverting types of allpass filters, and also exhibits high-output impedances, which are easy cascading in the current-mode operation. As an application of the proposed CDTA-based allpass section, a current-mode quadrature oscillator is realized. PSPICE simulation results are given to confirm the theoretical analysis.     

Novel approach to exact design of digital LDI allpass networks

A novel approach is proposed for the direct z-domain design and synthesis of arbitrary-order digital LDI allpass networks. This leads to the development of two LDI allpass network structures, one of which is completely new whereas the other has recently been derived indirectly by using the bilinear LDI design technique. Both structures lend themselves to fast two-cycle operation independent of the order of the corresponding transfer function. In addition, they are minimal in the number of digital multipliers and require only one unit-delay more than the minimum number possible.<>     

Versatile universal voltage-mode filter employing DDCCs

A new versatile universal voltage-mode biquad with three inputs and five outputs using only two differential difference current conveyors (DDCCs), two grounded capacitors, and three resistors is proposed. The proposed configuration which can be used as either a single-input five-output filter or three-input two-output filter and which can simultaneously realize all five different generic filtering lowpass, bandpass, highpass, bandstop, and allpass signals is unlike the previously reported works and still enjoys (i) the employment all grounded capacitors, (ii) no need to employ inverting-type input signals, (iii) orthogonal control of the resonance angular frequency and the quality factor, (iv) simultaneous realization of lowpass, bandpass, highpass, bandstop, and allpass responses for the single-input five-output filter, and (v) no need to impose component choice to realize all five generic responses for the three-input two-output filter.