Rosenstark-like Representation of Feedback Amplifier Resistance
ABSTRACT We propose a representation and a related methodology for evaluating the exact input and output resistances of feedback amplifiers. The approach is based on the generalization of the Rosenstark theorem. Indeed, it requires the computation of two resistances (direct and asymptotic) each one evaluated in one of the two ideal and extreme conditions of the return ratio (zero or infinity). Due to these characteristics, the representation allows one to understand what happens to a feedback amplifier resistance in the case of absence of feedback or in the ideal case of infinite feedback.
- 01/2002; Kluwer Academic Publishers., ISBN: 0792376439
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ABSTRACT: Signal flow theory offers a computationally efficient and accurate design-oriented alternative to traditional feedback network analysis techniques. The latter often suffer from burdensome algebra and questionable approximations that render the impact of a given feedback loop on achievable network performance obscure. Unlike the classical literature, which formulates signal flow theory in terms of relatively vague algebraic concepts, the author develops signal flow theory and associated circuit analysis methods exclusively in terms of elementary network theoretic principles. Aside from confirming the circuit analysis property of signal flow techniques, the new perspective underlying their theoretical development offers considerable insight into the genuinely difficult problem of implementing stable, reliable, and effective feedbackIEEE Transactions on Circuits and Systems 05/1990;
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ABSTRACT: This two part paper addresses the genuinely difficult problem of efficiently analyzing and designing high performance analog feedback networks. Part I focuses on theoretical considerations and is therefore independent of device technology. Part II exploits the results formulated in Part I to develop models, computationally efficient analytical methods, and design criteria for six types of commonly used feedback architectures. The utility of these models, methods, and criteria is applicable to monolithic bipolar junction transistor, MOS, CMOS, and other device technologies. Part I specifically overviews the traditional mathematics that underlie the study of the circuit transfer, driving point impedance, and frequency response characteristics of analog feedback networks. This review establishes a foundation for developing a computationally efficient form of signal flow theory that embellishes these analytical methods and illuminates design-oriented insights that are otherwise obscured by the tedium pervasive to traditional analyses. The new form of classical signal flow theory, which is a hybrid of signal flow and two-port network theories, is introduced in Part I and developed fully in Part II. This hybrid method of feedback circuit analysis allows for an efficient assessment of the gain, bandwidth, sensitivity, stability, and input/output impedance characteristics of a broad variety of global feedback loops. Additionally, the method complements the task of formulating engineering design guidelines for feedback network design by highlighting the attributes and limitations implicit to specific types of feedback configurations.Analog Integrated Circuits and Signal Processing 10/1998; 17(3):175-194. · 0.55 Impact Factor