Current-mode variable frequency quadrature sinusoidal oscillators using two CCs and four passive components including grounded capacitors: a supplement

摘要

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].