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Circuits and Systems, IEEE Transactions on

Issue 2 • Date February 1979

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Displaying Results 1 - 9 of 9
  • Comments on "The Absolute Stability of High-Order Discrete-Time Systems Utilizing the Saturation Nonlinearity"

    Page(s): 138 - 140
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    It is shown that passivity properties introduced by Mitra for saturation type overflow nonlinearities determine this nonlinear characteristic up to a scaling factor, and that a stability criterion based on these passivity properties can be derived in a different way. It is indicated that this alternative derivation allows a generalization of the criterion to systems with more than one saturation nonlinearity. View full abstract»

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  • Notes on n-Dimensional System Theory

    Page(s): 105 - 111
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    This paper makes three observations with regard to several issues of a fundamental nature that apparently must arise in any general theory of linear n-dimensional systems. It is shown, by means of three specific interrelated counterexamples, that certain decomposition techniques which have proven to be basic forn = 1and2are no longer applicable forn geqslant 3. In fact, forn geqslant 3, at least three equally meaningful but inequivalent notions of polynomial coprimeness emerge, namely, zerocoprimeness (ZC), minor-coprimeness (MC), and factor-coprimeness (FC). Theorems I and 3 clarify the differences (and similarities) between these concepts, and Theorem 2 gives the ZC and MC properties a useful system formulation. (Unfortunately, FC, which in our opinion is destined to play a major role, has thus far eluded the same kind of characterization.) Theorem 4 reveals that the structure of 2-variable elementary polynomial matrices is completely captured by the ZC concept. However, there is reason to believe that ZC is insufficient forn geqslant 3but a counterexample is not at hand. The matter is therefore unresolved. View full abstract»

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  • Nodal analysis of switched-capacitor networks

    Page(s): 93 - 105
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    Switched-capacitor (SC) networks comprise capacitors interconnected by an array of periodically operated switches. Such networks are particularly attractive in light of the high circuit density possible with MOS integrated circuit technology and hybrid integrated circuits using thin-film and silicon technology. The paper describes the analysis of SC networks by using nodal charge equations. It is shown that SC networks are time-variant sampled-data networks, which can be viewed as tandem connected four-ports in thez-domain. One pair of ports is viewed as a signal path corresponding to the even time slots, the other pair of ports as a path corresponding to the odd time slots of the periodically operated switches. In a subsequent publication the authors will show how four-port equivalent circuits in the z-domain of six basic building blocks can be used for the description of any SC network. This method allows the direct use of traditional network analysis tools like the transmission matrix for deriving transfer functions. The method ultimately leads to a two-port analysis of SC networks in which conventional two-port theory can be applied. View full abstract»

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  • Solvability of bond graph junction structures with loops

    Page(s): 130 - 137
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    The purpose of this paper is to present a simple computational rule for determining the solvability of the linear junction structure equations of multiport systems. This rule is derived from the bond graph for the system. Three types of junction structures are considered; namely, simple, weighted, and general. Weighted junction structures include transformers and general junction structures include gyrators. The concept of causal loop gain is defined, and its calculation is indicated. Necessary and sufficient conditions, based on the loop gain, are given regarding the solvability of linear junction structure equations. Examples are presented highlighting the results. View full abstract»

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  • Active compensation of opamps

    Page(s): 112 - 117
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    A novel active compensation method for the finite gain bandwidth of operational amplifiers, when used in voltage-controlled voltage source structures, is given. In this method, a universal active compensation scheme is proposed which can be used with operational amplifier voltage-controlled voltage sources, when looked upon as a general threeport active building block. It is shown that phase shifts contributed by imperfect operational amplifiers are virtually eliminated over an extended frequency range. Experimental resnits are presented. View full abstract»

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  • Sequence discriminators and their use in frequency division multiplex-communication systems

    Page(s): 117 - 129
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    A simple theory of networks exhibiting sequence discrimination and their use for producing quadrature signals is first presented. A channel unit employing sequence discriminators (SD's), namely, passive (RC), passive with feedback, and active designs are discussed. A channel unit employing SD's and the associated modulation and demodulation schemes are suggested. Statistical sensitivity results and experimental results using thick film resistor and NPO chip capacitor implementations are also given. These indicate that the (SD) approach for single-sideband generation and detection is very promising in FDM applications. This technique which uses resistors, capacitors, and commercial integrated circuits is simple to implement and requires no specially developed technologies. View full abstract»

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  • An RC-active all-pass section with reduced magnitude response error

    Page(s): 144 - 148
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    The problem of magnitude response deviations in RC active all-pass networks due to limited amplifier gains is discussed. Conditions for reduced errors are established and an RC active network satisfying the prescribed conditions is presented. Comparative experimental evidence is also presented which confirms the relative independence of the proposed network' s magnitude response on the amplifier gain-bandwidth products. View full abstract»

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  • Analytical and experimental evaluation of a switched-capacitor filter and remarks on the resistor/switched-capacitor correspondence

    Page(s): 140 - 144
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    A simple high-pass filter consisting of two capacitors and a switch is analyzed in detail, and is used as a vehicle to show the type of considerations involved in switched-capacitor circuits. Theoretical results are compared to experimental. The validity of approximating switched capacitors by resistors is examined for the above circuit. View full abstract»

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  • Charge-routing networks

    Page(s): 81 - 92
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    The fundamental techniques for charge manipulation achievable with MOS charge-coupling technology include storage, transfer, splitting, combining, insertion, and extraction. We idealize and generalize these operations to define a general class of networks for discrete-time linear filtering. A p-phase charge-routing network (CRN) consists of a collection of storage cells divided into p subgroups and a routing procedure controlled by a p-phase clock. During a particular clock phase, charge is routed from a particular subgroup of storage cells into another subgroup. In this manner charge is routed successively through each subgroup of cells and a periodically time-varying linear discrete-time network is defined by specifying matrices of weight values associated with the routing procedure. Analysis of ap-phase CRN yields a reduced system of linear time-invariant dynamic state equations convenient for signal-processing studies. Necessary and sufficient conditions on such a system of state equations are given for realizability as ap-phase CRN. The varied structures attainable with CRN's can realize infinite inpulse-response filter transfer functions. However, certain fundamental restrictions exist on the class of transfer functions realizable with CRN's. In particular, we show the existence of forbidden zones within the unit circle in the z-plane, where poles (or natural modes) of a CRN cannot occur. A parallel can be drawn between classical RC networks and charge-routing networks. Both types of networks have substantial restrictions on the class of filters they can by themselves realize. For RC networks, we know the limitations can be overcome by the addition of another component (inductance or operational amplifier). A similar potential may exist for CRN's. This paper provides a foundation for a general theory that could offer realizability conditions and sythesis procedures for discrete-time filtering via charge routing networks. View full abstract»

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