Abstract
This letter comments on the recently published paper in [1] which provides realizations of minimum component quadrature sinusoidal oscillators. On re-examination of the ‘Type 3’ oscillator circuits in [1], it has been found that the circuits actually suffer from ‘latch up’ problem due to use of incorrect polarity of the CCII based negative-impedance convertor. This problem has been corrected (without altering the characteristic equation) by swapping the impedances at y and x terminals. Explicit quadrature current outputs are derived similarly as done in [1].
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References
Lahiri, A. (2010) Current-mode variable frequency quadrature sinusoidal oscillators using two CCs and four passive components including grounded capacitors. Analog Integrated Circuits and Signal Processing. doi:10.1007/s10470-010-9571-8.
Abuelma’atti, M. T. (2010) New two CFOA-based sinusoidal RC oscillators with buffered outlet. Analog Integrated Circuits and Signal Processing. doi:10.1007/s10470-010-9582-5.
Acknowledgment
The author would like to thank Prof. Dr. Raj Senani and Prof. Dr. Dalibor Biolek, for their valuable comments.
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Lahiri, A. Current-mode variable frequency quadrature sinusoidal oscillators using two CCs and four passive components including grounded capacitors: a supplement. Analog Integr Circ Sig Process 68, 129–131 (2011). https://doi.org/10.1007/s10470-011-9635-4
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DOI: https://doi.org/10.1007/s10470-011-9635-4