An useful modification of well known signal flow graph technique for the circuit synthesis is described in this paper in order to obtain the filters working in the current mode, with maximally variable parameters, namely characteristic frequency, quality factor, bandwidth and basic gain. Procedure is based on reciprocal conversion of the branch variables (V→I and I→V) with the adjustable conversion constants. The obtained structures are discussed in detail and then is described an example of current-mode multifunctional RC active biquadratic filter, what is today very popular analogue application. Theoretic assumptions are supported by experimental results using modern functional blocks CC II(-).
PL
Opisano metodę analizy grafów przepływowych do projektowania filtrów pracujących w trybie prądowym z uwzględnieniem charakterystyki częstotliwościowej, współczynnika jakości, pasma I wzmocnienia. Procedura bazuje na odwrotnej konwersji zmiennych. Otrzymaną strukturę filtru przedyskutowano na przykładzie wielofunkcyjnego filtru RC w trybie prądowym. Analiza teoretyczna poparta jest wynikami.
A new method of first-, second-order and multiparameter symbolic sensitivity determination based on the nullor model of active devices and modified Coates flow graph is presented. Rules for a symbolic reduction of nullor circuit complexity are described. An algorithm performs symbolic sensitivity analysis with respect to various circuit parameters appeared not only at one location in the modified Coates flow graph. Advantages of the method suggested are that, the matrix inversion is not required and the main drawback of some methods based on the adjoint graph, i.e. the necessity to analyze the corresponding graph twice, is avoided. Illustrative examples on symbolic sensitivity analysis are given.
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