Narrow Results

A sequential method of analysis of nullor-based active network is presented. The symbolic circuit analysis can be performed easily with the knowledge of properties of circuit elements including nullor elements. The practical circuit examples are given to demonstrate the feasibility of the proposed approach.

Genetic Algorithm (GA) applications in analog design circuits play an important role with promising results. This paper introduces a proposed methodology based on the genetic algorithm and the symbolic representation to generate equivalent op-amp configurations for well-known filters. The proposed methodology is applied to the Tow-Thomas (TT) filter to generate 168 different configurations. Moreover, it is also applied on the KHN filter resulting in 30 equivalent circuits for each type. A part of the generated realizations is tested through simulations using PSPICE simulator and the simulation results determine the number of accepted circuits. A simulation comparison between the original filter configuration and some of the accepted configurations is done. Fortunately, a better performance compared to the original configuration is obtained from some generated circuits.

In this paper, the method for the design automation of a narrow band-pass amplifier, and hence the amplifier tuned oscillator is discussed. A fixator approach is utilized in this method to design the narrow band-pass amplifiers and a reference circuit is required for this process. The fixator–norator pair helps to generate an extra sub-circuit, generally the feedback network; the addition of this sub-circuit in the actual amplifier circuit will modify the frequency response of the amplifier. The amplifier now behaves like an active narrow band-pass filter, which exactly follows the frequency response of the model circuit. This can be turned into an oscillator by providing positive feedback. Such a circuit possesses independent frequency and amplitude control. Hence, the re-designed circuit can be employed as an active filter or an oscillator at the selected center frequency. In addition to the technical merits, the proposed method has pedagogical importance. Few case studies are worked out in this paper to demonstrate the method.