Generalized Immittance Converter Research Articles

Optimal design of a fractional order immittance in the second quadrant with wide CPZ

This paper presents a design technique to realize fractional order (FO) immittance in the second quadrant of the impedance plane, using Bruton’s generalized immittance converter (GIC). Design guidelines are developed based on a sub-optimal analysis of phase error resulted by non-ideal op amps. The analysis takes into account finite open-loop dc gain and finite unity-gain frequency of practical op amps and aim to maximize the constant phase zone for a given phase band specification. The fractance of the realized fractor can also be tuned to a desired value by varying one of the GIC resistances. Several simulations and experimental validations are demonstrated. Also, high Q, FO bandpass filter with wide tuning range is presented as an application of the designed obtuse angle fractor.

Novel realization of GIC based wave digital filters using Al-Alaoui transform

By using the concepts of wave characterization, Al-Alaoui transform and generalized immittance converter (GIC), a new digital GIC structure is proposed which is capable of realizing all the standard second-order digital filter sections. The Al-Alaoui transform is utilized for reference circuit discretization, leading to development of second-order digital filter sections which possess better noise properties than the conventional GIC and GIC discretized using the fractional bilinear transform. The proposed second-order digital filter sections are used as building blocks in cascade synthesis of filter. Two design examples are considered to analyze the effectiveness of the proposed filter sections and their comparison with the other filter sections is performed in terms of quantization noise and approximation to analog filter response. The proposed synthesis yields lowpass and highpass filters that have a better signal to noise ratio and better approximation of the analog filter frequency response than the conventional GIC digital filters and fractional GIC digital filters.

A new realization of wave digital filters using GIC and fractional bilinear transform

In this paper, a new class of second-order digital filters is developed by using the concept of wave characterization, fractional bilinear transform and generalized immittance converter (GIC). These second-order digital filter sections are used as building blocks in cascade synthesis. During the realization procedure, fractional bilinear transform is utilized for analog to digital conversion to get more competent digital filter sections. The noise performance of the proposed filter sections is compared with that of already known GIC second order digital filter sections. The proposed synthesis yields lowpass and highpass filters with ameliorated signal to noise ratio in comparison to that of the conventional GIC digital filters.

A design of MOSFET‐C impedance simulation circuits based on a GIC

AbstractThis paper proposes a systematic design method of MOSFET‐C impedance simulation circuits based on a generalized immittance converter (GIC). The design method can realize inductance simulation circuits, capacitance multipliers and frequency‐dependent negative resistances (FDNRs) only by MOSFETs, capacitors and two operational amplifiers. Although MOSFETs are used instead of passive resistors, the realized impedance simulation circuits have good linearity since the nonlinearity caused by MOSFETs are cancelled out. The proposed design method derives three inductance simulation circuits, five capacitance multipliers and two FDNRs systematically from a GIC. All of them are summarized in this paper. As an example, inductance simulation circuits are designed by using the proposed design method. The inductance simulation circuits are applied to a filter realization and validity of the design method is confirmed by HSPICE simulations. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Design of Stable Circularly Symmetric Two-Dimensional GIC Digital Filters Using PLSI Polynomials

A method for designing stable circularly symmetric two-dimensional digital filters is presented. Two-dimensional discrete transfer functions of the rotated filters are obtained from stable one-dimensional analog-filter transfer functions by performing rotation and then applying the double bilinear transformation. The resulting filters which may be unstable due to the presence of nonessential singularities of the second kind are stabilized by using planar least-square inverse polynomials. The stabilized rotated filters are then realized by using the concept of generalized immittance converter. The proposed method is simple and straight forward and it yields stable digital filter structures possessing many salient features such as low noise, low sensitivity, regularity, and modularity which are attractive for VLSI implementation.

New Modular Multidimensional Digital Filter Structures

New multidimensional digital structures that use the concept of a generalized immittance converter are presented in this paper. The proposed filter structures are regular and modular, and they realize multiple transfer functions simultaneously; hence, they are attractive for very large-scale integration implementation. It is shown that these filter structures can be obtained by using a few specific digital modules as building blocks. The arrangements of the modules and the values of the multiplier constants that are used in these modules can be obtained directly from the specified discrete transfer function by using a computer program.

Realization of Modular Multidimensional Complex Digital Filters Using GIC Concept

It is known that complex digital filters possess certain advantages over real digital filters in processing complex signals such as increased computational speed and efficiency. In this paper, a simple and systematic procedure which can be implemented through a computer program is presented for realizing a specific class of multidimensional (M-D) complex digital filters. The proposed filter structures are derived from analog reference configurations comprising generalized immittance converters and resistors by making use of wave concept. These filters possess many salient properties such as low noise, low sensitivity and capability of realizing multiple transfer functions simultaneously which are inherited from the reference analog filters they are derived from. These features make them attractive for very large-scale integrated (VLSI) implementation. It is shown that the proposed filter structures can be obtained directly from the specified M-D discrete transfer function without the need for realizing any analog reference configuration.

Design of Two-Dimensional Pseudorotated Digital Filters Using Concept of Generalized Immittance Converter

A new realization procedure based on the concept of the generalized immittance converter (GIC) is proposed for two-dimensional (2D) pseudorotated digital filters that have circularly symmetric magnitude response characteristics. By applying a suitable transformation to a one-dimensional stable discrete transfer function, the 2D discrete transfer function of the corresponding pseudorotated filter is obtained. This transfer function is then realized by using a direct computer-based method. It is shown that four types of GIC pseudorotated filter structures can be obtained by interconnecting a few specific types of digital modules. The modularity and regularity nature of these filters make them attractive for very large-scale integration implementation.

A new realization method for multidimensional GIC digital filters

A simple and straightforward procedure for the realization of multidimensional digital filters which are based on the concept of generalized immittance converter is presented. It is known that these digital filters possess many salient features such as low noise, low sensitivity, absence of limit cycles and capability of realizing multiple transfer functions. Unlike the other known methods, which use analog transfer function as the basis, the method proposed in this paper uses the discrete transfer function directly for realization. It is shown that the required details of the resulting filter structure, namely, the organization of the different adaptors and the values of the multiplier constants can be obtained directly from the specified discrete transfer function.

Design of 2-D pseudorotated digital filters with multiple outputs

In this paper, a design procedure for 2-D pseudorotated filters is presented. The procedure employs reference analog configurations comprising generalized immittance converters and resistors. It is shown that the digital filters designed using this approach are capable of realizing multiple transfer functions simultaneously, and hence are attractive for VLSI implementation.

Realization of complex digital filters based on the concept of the generalized-immittance converter

A systematic method for the realization of complex digital filters based on the concept of the generalized-immittance converter is presented. The method is simple to apply and can be used to realize arbitrary one-dimensional and multidimensional complex digital filters. The method is then used to realize a fourth-order Chebyshev filter, and the sensitivity performance of the filter is compared with that of other known low-sensitivity structures.

Fast parallel realization of IIR adaptive filters

A parallel realization based on the voltage-conversion generalized-immittance converter is used for the implementation of adaptive IIR filters. Through this approach, the convergence rate of the parallel realization is substantially increased, and becomes comparable or higher than that in the direct-form realization and much higher than that in the lattice realization. The paper deals with the reasons that lead to the improved performance and provides extensive experimental results that illustrate the fast convergence, reduced computational complexity, and improved robustness.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

NEW FIRST-ORDER COMPLEX DIGITAL-FILTER SECTIONS AND THEIR APPLICATION FOR THE REALIZATION OF IIR FILTERS

New first-order complex digital-filter sections are realized using the concept of the generalized-immittance converter. These sections are then employed for the realization of infinite impulse response digital filters with real coefficients. The filters obtained with the proposed sections have sensitivity and roundoff noise properties that are comparable to those of other structures of this class reported earlier.

Realization of multidimensional GIC digital filters

A realization method for multidimensional Nth-order infinite-impulse-response (IIR) digital filters is proposed. A systematic procedure is presented for synthesizing analog reference networks comprising generalized immittance converters, and resistors, which realize M-variable Nth-order transfer functions. Digital-filter structures are then derived from these reference networks using the wave characterization. The proposed structures are canonic with respect to the number of multipliers and constitute a new class of multidimensional wave digital filters, distinct from the class of wave digital filters derived from doubly terminated LC networks. The realization method is general and relatively simple to apply, and leads to some interesting structures including structures with multiple outputs. >

Limit-cycle free complex biquad recursive digital filters

A novel type of complex biquad recursive digital structure, based on the concept of a generalized immittance converter, is discussed. Orthogonal filters which are widely used in time-division multiplexing-frequency-division multiplexing (TDM-FDM) transmultiplexers can be obtained as a special class of these complex biquads. It is shown that the proposed structure is completely free from zero-input limit cycles under linear conditions, and further, that the stability under finite arithmetic conditions can be achieved using the technique of magnitude truncation. It is also shown that for this structure, the stability of the forced response can be ensured for certain types of overflow nonlinearities.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Digital-filter structures based on the concept of the voltage-conversion generalized-immittance converter

By using the concept of the voltage-conversion generalized-immittance converter, a general biquadratic digital-filter structure is obtained which can realize all the standard, second-order, digital-filter sections. Then, through the application of the principle of transposition, a multiple-output structure is obtained which can realize either individually or simultaneously, all the standard second-order digital-filter sections. The proposed structures, can be stabilized with respect to limit-cycle oscillations. Further, the structures obtained by transposition have the unique property of allowing a choice between the elimination of limit cycles and the reduction of roundoff noise. The authors conclude with a comparison of the proposed structures relative to the direct canonic and section-optimal structures with respect to output roundoff noise and sensitivity.

Improved GIC digital filter structures

A procedure is proposed which leads to a reduction in the number of adders in a class of digital filter structures based on the generalized-immittance converter (GIC). This is then used to obtain more economical GIC structures. For example, a second-order digital equalizer is obtained which requires only two unit delays, two multipliers, and six adders. Further, it is shown that the improvements are brought about without degrading the low-noise feature of the original structures.

Design of a universal active filter using Generalized‐Immittance Converter Biquads

Abstract A general GIC (Generalized‐Immittance Converter) section capable of realizing any second‐order biquadratic functions is described first. It employs at most three operational amplifiers and a few passive elements. Using this approach, a Universal Active Filter (UAF) building block has been obtained, and thus any filtering functions, such as lowpass (LP), highpass (HP), bandpass (BP), allpass (AP) and notch (N) functions, can be easily constructed. The resulting filter realizations are shown to have low active and passive sensitivity to element variations. The high‐frequency performance limitations imposed by the finite bandwidth of the operational amplifier have also been examined. The proposed scheme has been compared with that of the state‐variable realizations exhibited by Kerwin, Huelsman and Newcomb (KHN) and been found to offer several attractive features as compared to this realization. The design procedure is illustrated by a sixth‐order elliptic bandpass filter together with theoretical a...

Comparison of the effects of quantization on digital filters

The fixed-point roundoff noise and coefficient sensitivity properties of the cascade canonic, Sedlmeyer-Fettweiss wave digital filter, the digital generalized immittance converter filter, and the Swamy-Thyagarajan wave digital filter are examined. The relative power spectral density and the statistical wordlength of each structure are computed.

Network structure and minimum number of elements in the topological realization of generalized immitance converters

AbstractThis paper presents a basic discussion for all possible topological minimal realizations of the generalized immittance converter (GIC), which is one of the most important functional two‐ports. In other words, a systematic derivation is presented for the lower bounds for the number of necessary elements in the topological realization of a GIC using nullors and positive resistors, as well as for all of the two‐graphs (voltage and current graphs) for the minimal realization of a GIC from the port characteristics, based on the necessary and sufficient condition for the port‐parameter of an N‐port to be topologically non‐zero. As is anticipated from the general expressions for the port‐parameters, the network structure essentially depends on whether or not the gain of the GIC has unit magnitude. Consequently, the discussion is divided into the cases where the gain of the GIC is of unit magnitude and where it is not. Using the result of this paper, all minimal realizations for GIC, including the newly derived ones, can be derived systematically and easily [4, 9].