# Open-circuit voltage transfer-function synthesis using the generalized positive impedance converter

TL;DR: In this paper, an open-circuit voltage transfer function synthesis procedure is presented that realizes any arbitrary real rational function in the complex variable s. The procedure makes use of an active device referred to as the generalized positive impedance converter (GPIC).

Abstract: An open-circuit voltage transfer-function synthesis procedure is presented that realizes any arbitrary real rational function in the complex variable s. The procedure makes use of an active device referred to as the generalized positive impedance converter (GPIC). The synthesis procedure yields a network realization that 1) requires the minimum number of capacitors necessary for the synthesis, 2) is compatible with integrated-circuit fabrication techniques, and 3) has low sensitivity.

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TL;DR: In this article, a systematic RC-active network synthesis procedure for the realization of second-order transfer functions is proposed, which employs three operational amplifiers and no isolation amplifiers are necessary.

Abstract: A systematic RC -active network synthesis procedure for the realization of second-order transfer functions is proposed. The realization employs three operational amplifiers and no isolation amplifiers are necessary. The sensitivity of the resulting networks to passive element variations has been found to be low. The sensitivity to variations in the active elements has been made very low. A design is given in which tuning can be achieved by trimming only resistors. The design is particularly attractive for high- Q realizations. The stability properties and the influence of the finite bandwidth of the amplifiers are examined. The proposed realization has been compared with those of Kerwin, Huelsman, and Newcomb, of Tarmi and Ghausi, and of Thomas, and found to offer several attractive features as compared to these realizations. The design procedure was used to obtain a sixth-order elliptic bandpass filter. Experimental results show close agreement between theory and practice. Further, these results indicate that these realizations are insensitive to temperature and power supply variations.

38 citations

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TL;DR: In this paper, a systematic RC-active network synthesis procedure for the realization of second-order transfer functions is proposed, which employs a single generalized impedance converter which can be implemented by using only two operational amplifiers.

Abstract: 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.

32 citations

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06 Nov 1985TL;DR: In this paper, a general purpose digitally controlled analog filter is presented, which is a cascade of second-order sections that are individually programmed to achieve any filtering toplogies, and two-binary words are used to control the pole frequency omega p and selectivity Qp of each section independently.

Abstract: : In this research a general purpose digitally controlled analog filter is presented. The novel design is a cascade of second-order sections that are individually programmed to achieve any filtering toplogies. Two-binary words are used to control the pole frequency omega p and selectivity Qp of each section independently. Each second-order section is a Generalized-Immittance Converter (GIC) biquads which are known for their high stability and low active and passive sensitivity. CMOS switches are used to electronically relocate the minimum number of passive elements to achieve function programmability. Switches are also used to select the number of cascaded sections to realize higher order transfer functions. (Theses)

5 citations

##### References

More filters

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TL;DR: In this paper, generalized-immittance converters are used in which the input immittance is proportional to s 2 + load immittance, and the resulting realizations are shown to have low sensitivity to element variations.

Abstract: A general synthesis procedure capable of realizing any stable transfer function is described; generalized-immittance converters are used in which the input immittance is proportional to s^{2} \times load immittance. The resulting realizations are shown to have low sensitivity to element variations. The sensitivity in realizations of second-order transfer functions is independent of the selectivity and it is shown to be much lower than the sensitivity in realizations using positive-gain amplifiers or negative-immittance converters. A unique feature is that in some cases the same circuit can be used as a low-pass as well as a high-pass filter. The synthesis procedure is illustrated by examples and experimental results.

49 citations

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TL;DR: In this article, the nodal admittance matrix of a six-node resistive network with two infinite gain amplifiers embedded in it is discussed, and element values are obtained to realize the required analog circuits with a minimum number of components.

Abstract: The properties of three terminal positive and negative impedance convertors are defined in terms of the cofactors of the indefinite nodal admittance matrix, the special cases of the ideal transformer, power amplifier, and voltage and current inverting negative impedance convertors being considered in detail. The nodal admittance matrix of a six-node resistive network with two infinite gain amplifiers embedded in it is discussed, and element values are obtained to realize the required analog circuits with a minimum number of components. The analog circuits obtained are simple to set up and are ideal for demonstrating and testing applications of impedance convertors to filter network realizations. Of particular interest is the circuit obtained for the case of a loaded, phase-reversing, positive impedance convertor, which employs only one operational amplifier and four resistors in a bridge circuit, which is thought to be novel, and which can be extended by the introduction of a second amplifier and three resistors to produce a simple realization of a negative impedance invertor (NIV).

6 citations