The Journal of Engineering (Jun 2014)

Generation of equivalent forms of operational trans-conductance amplifier-RC sinusoidal oscillators: the nullor approach

  • Raj Senani,
  • Manish Gupta,
  • Data Ram Bhaskar,
  • Abdhesh Kumar Singh

DOI
https://doi.org/10.1049/joe.2013.0200

Abstract

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It has been shown in two earlier papers published from this study that corresponding to a given single-operational trans-conductance amplifier (single-OTA)-RC and dual-OTA-RC sinusoidal oscillators, there are three other structurally distinct equivalent forms having the same characteristic equation, one of which employs both grounded capacitors (GC). In this study, an earlier nullor-based theory of generating equivalent op-amp oscillator circuits, proposed by the first author, is extended to derive equivalent OTA-RC circuits which discloses the existence of an additional number of equivalent forms for the same given OTA-RC oscillators than those predicted by the quoted earlier works, and thereby considerably enlarging the set of equivalents of a given OTA-RC oscillator. Furthermore, the presented nullor-based theory of generating equivalent OTA-RC oscillators results in three additional interesting outcomes: (i) the revelation that corresponding to any given OTA-RC oscillator there are two ‘both-GC’ oscillators (and not merely one, as derived in the quoted earlier works); (ii) the availability of explicit current outputs in several of the derived equivalents and (iii) the realisability explicit-current-output ‘quadrature oscillators’ in some of the generated equivalent oscillators. The workability of the generated equivalent OTA-RC oscillators has been verified by SPICE simulations, based on CMOS OTAs using 0.18 µm CMOS technology process parameters, and some sample results are given.

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