Generalized Impedance Converter Research Articles

Chaos in a series circuit with a nonlinear capacitor and a nonlinear inductor

This paper proposes a nonlinear circuit that generates chaotic oscillations. The proposed nonlinear circuit includes a nonlinear capacitor and a nonlinear inductor by using Generalized Impedance Converters. Both computational experiments and experiments on real circuits show that the region for chaotic oscillation is very wide, demonstrating that the proposed circuit is effective as a chaos generator. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(2): 35–42, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10361

Current source design for electrical impedance tomography

Questions regarding the feasibility of using electrical impedance tomography (EIT) to detect breast cancer may be answered by building a sufficiently precise multiple frequency EIT instrument. Current sources are desirable for this application, yet no current source designs have been reported that have the required precision at the multiple frequencies needed. We have designed an EIT current source using an enhanced Howland topology in parallel with a generalized impedance converter (GIC). This combination allows for nearly independent adjustment of output resistance and output capacitance, resulting in simulated output impedances in excess of 2 GΩ between 100 Hz and 1 MHz. In this paper, the theoretical operation of this current source is explained, and experimental results demonstrate the feasibility of creating a high precision, multiple frequency, capacitance compensated current source for EIT applications.

Chaos in a Series Circuit with Nonlinear Capacitor and Nonlinear Inductor

This paper proposes a nonlinear circuit that generates chaotic oscillations. The proposed nonlinear circuit includes a nonlinear capacitor and a nonlinear inductor by using Generalized Impedance Converters. Both computational experiments and experiments on the real circuits exhibit that the region for chaotic oscillation is very wide, which show that the proposed circuit is effective for a chaos generator.

A Novel Generalized Impedance Converter Using Single Second Generation Current Conveyor

A generalized impedance converter (GIC) using single CCII(−) is presented. The circuit uses no matching constraints and provides a wide variety of ideal component simulators and multipliers. The GIC can also be made tunable by using CCCII(−) instead of CCII(−). The proposed GIC is verified using SPICE with excellent results.

Characteristics of low-frequency parametric magnetic sensor

In this paper, a low-frequency parametric magnetic sensor with a magnetic ribbon and an Antoniou general impedance converter is described. A low-frequency parametric magnetic sensor with a parametric oscillation frequency of about 20 kHz is examined. We show that the sensor has a sensitivity of 1.04 mV/sub p-p//(A/m) without any amplifier and detects a constant output voltage independent of frequency in the band from 1 Hz to 1 kHz.

Electronically tunable generalized impedance converter structures

New generalized impedance converter (GIC) structures realizable with four and six active components (operational amplifiers (OA) and operational tansconductance amplifers (OTA)) in the grounded and floating configurations, respectively, only three passive elements are derived. The resulting circuits enable a wide range linear tuning of impedance through the control voltage or current of the ()TA and are expected to find applications in tunable circuits (filter and oscillator for instance). The viability of the proposed structures has been confirmed by SPICE simulation results.

CMOS-based integrable electronically tunable floating general impedance inverter

An integrable electronically tunable general impedance inverter (EGII), implemented by a MOS circuit design technique, is described. The driving point impedance of the EGII, that is inversely proportional to a given impedance, can be a positive or a negative value and can be electronically varied. The realization scheme employs proposed voltage-to-current transducers (VCTs) that are designed based on a linearizing technique, as basic circuit building blocks. The applications of the EGII as a gyrator, a general impedance converter and a floating capacitance multiplier are discussed. Experimental and simulation results that demonstrate the characteristics of the EGII are included.

Analog Universal Active Device: Theory, Design and Applications

This paper introduces the concept of what we call analog Universal Active Device (UAD), as a step forward from Operational Amplifiers and other recently proposed active devices. The model for such a device is nothing but a two port classically known as Nullor. To obtain practical implementations of the UAD, or Nullor, a unified aproach is proposed. The basis of the approach is the use of a single cell consisting of a voltage and current buffer, also known as negative second-generation Current Conveyor (CCII –). We obtained the four most simple implementations for the UAD as a paradigm of more complex ones. Non ideal effects of these practical implementations are theoretically analysed, particularly parasitic impedances associated to the interconnections of the CCII – cells, and then their influence in some simple amplifier stages. It is demonstrated that while any UAD implementation can be used in a given application, its performance is strongly dependent on its implementation. Also, a novel floating structure for a General Impedance Converter (GIC) type impedance, containing two UADs, is suggested. Simulation results are given supporting the ideas presented here.

Restriction on realization of single‐amplifier impedance‐converter and its application to LCR filter simulation

AbstractThis paper proposes a method to realize single‐amplifier impedance converters (SAICs), while a conventional general impedance converter (GIC) for an active RC filter requires two operational amplifiers. First, various restrictions required for realizing an SAIC were investigated. Then a method of realizing an SAIC was described which utilizes the property of a grounded active RC two‐port circuit having an impedance‐conversion effect; and the SAIC was applied to the simulation of an LCR filter. an SAIC can approximately simulate an arbitrary circuit with some restricted circuit constants, although the range of circuits which can be simulated exactly is limited. As examples, an asymmetrical sixth‐order BPF and a symmetrical sixth‐order BPF were constructed and their experimental results agreed well with the theoretical values.

On the design of RC-active highpass filters using 2-OA GIC

The design philosophy for RC-active highpass filters has not received as much consideration as lowpass and bandpass structures. The highpass filter (HPF) has a reasonable passband behaviour at high frequencies, at least up to 10 times the corner frequency. This is difficult to achieve due to the deteriorating behaviour of the practical operational amplifier (OA). In high order ladder structures, widely used because of their low sensitivity, improving the HPF behaviour is equivalent to designing a high quality grounded inductor at high frequencies. This evolves a procedure for the appropriate design of 2-OA GIC (generalized impedance converter) simulated inductances, suitably compensated for the nonideal aspects of the OA such as finite bandwidth, signal handling capability, output resistance, etc. Experimental results for 0.1 dB 7th order Cauer-Chebyshev highpass filters with corner frequencies at 10 KHz and 30 KHz are presented to evaluate the procedure. The two filters are studied at different signal levels using two types of OAs with gain-bandwidth products of 3 and 4.5 MHz.

Equivalent circuits for switched-capacitor networks including recharging devices

Equivalent circuits for switched-capacitor (SC) networks including recharging devices are derived. Parasitic effects, like stray capacitances and nonideal op amps, are taken into account. As a result, the equivalent time-invariant network is split up into a frequency dependent impedance network and a purely (negative) resistive network which corresponds directly to the capacitor network of the SC-filter and allows for the loss compensation achieved by the recharging switching devices. In general, these two parts of the equivalent network are coupled via generalized impedance converters (GIC's).

Effect of amplifier imperfections on active networks

The deviation in the performance of active networks due to practical operational amplifiers (OA) is mainly because of the finite gain bandwidth product <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</tex> and nonzero output resistance <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R_0</tex> . The effect of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R_0</tex> on two OA impedances and single and multi-OA filters are discussed. In filters, the effect of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R_0</tex> is to add zeros to the transfer function often making it nonminimum phase. A simple method of analysis has been suggested for 3-OA biquad and coupled biquad circuits. A general method of noise minimization of the generalized impedance converter (GIC), while operating OA's within the prescribed voltage and current limits, is also discussed. The 3-OA biquadratic sections analyzed also exhibit noise behavior and signal handling capacity similar to the GIC. The GIC based structures are found to be better than other configurations both in biquadratic sections and direct realizations of higher order transfer functions.

Noise minimization in RC‐active filters using generalized impedance converters

AbstractA procedure has been given for minimizing the total output noise of a Generalized Impedance Converter (GIC), subject to constraints dictated by signal handling capability of the Operational Amplifiers and ease of microcircuit fabrication. The noise reduction is achieved only by the adjustment of RC elements of the GIC, and the total output noise after optimization in the example cited is close to the theoretical lower limit. The output noise of a higher‐order filter can be reduced by RC‐optimizing the individual GIC's of the active realization. Experimental results on a 20–24 kHz channel bank band‐pass filter demonstrate the effectiveness of the above procedure.

Transfer matrix realization using RC:GIC Networks

AbstractA general synthesis procedure for realizing any stable voltage transfer matrix using current‐conversion type generalized impedance converter (GIC)s is outlined. Each row of the transfer matrix is realized separately as an M‐input, single‐output grounded RC:GIC network where M is the number of columns in the transfer matrix. The realization procedure is illustrated by an example. Using this approach, a second‐order filter has been obtained capable of realizing simultaneously highpass, band‐pass and low‐pass transfer functions and using fewer passive components and operational amplifiers than the popular state‐variable realizations. The various sensitivities of the second‐order realizations are low and comparable to the state‐variable realizations. A similar method can be developed for current transfer matrix invoking duality and thus using the voltage‐conversion type GICs.

Design of RC-active networks using generalized-immittance converters

A systematic RC-active network synthesis procedure for the realization of second-order transfer functions is proposed. The realization employs a single generalized impedance converter which can be implemented by using only two operational amplifiers. The sensitivity to passive element variations are found to be low. The sensitivity to variations in the amplifier d.c. gain is minimized and found comparable to that in other low sensitivity structures. A design procedure is developed in which tuning can be achieved by trimming only resistors. With the exception of one case, second-order sections can be cascaded without additional isolating amplifiers. The stability properties as well as the influence of the finite bandwidth of the amplifiers are examined. The design procedure is used to obtain a sixth-order Chebychev low-pass filter, and a sixth-order elliptic band-pass filter. Experimental results show that these realizations are insensitive to temperature and power supply variations.

Electrical noise in low-pass FDNR filters

The electrical noise performance of generalized impedance converter (GIC) low-pass ladder structures is derived. The concept of frequency-dependent negative-resistance (FDNR) elements has allowed low-sensitivity high-order low-pass ladder structures to be realized directly from the corresponding LC prototype. The electrical noise appearing at the output of the low-pass FDNR realization is derived for the equiterminated low-pass Butterworth realization, and it is shown that the output noise power spectral density may be obtained from a suitable noise model of the GIC. Experimental verification of the output noise spectral density is given.

A transistor realization of the generalized impedance converter

A transistor realization of a generalized impedance converter (g.i.c.) is developed from an ideal nullor representation. The use of g.i.c.s for realizing low-sensitivity RC-active filters is well established and this new circuit overcomes the requirement for using two operational amplifiers in order to realize a g.i.c. The proposed transistor realization is a single-loop structure with the practical advantage of low output impedance; the use of this circuit in the realization of typical elliptic transfer functions is considered.

Biquadratic sections using generalized impedance converters

A low-sensitivity RC-active biquadratic section is proposed which employs a generalized impedance converter embedded in a simple passive RC-structure. This may be used to realize complex high-Q pole-pairs and transmission zeros. The multi-parameter sensitivity of the transfer function is independent factor. A high-quality narrow-band elliptic band-pass filter is given as a example.

A class of generalized impedance converters†

A new class of generalized impedance converters (GIC) consisting of generalized positive and negative impedance converters is defined and realized using operational amplifiers and passive elements. An example is included to illustrate their use in network synthesis.