Parasitic oscillation

Parasitic oscillation is an undesirable electronic oscillation (cyclic variation in output voltage or current) in an electronic or digital device. It is often caused by feedback in an amplifying device. The problem occurs notably in RF,[1] audio, and other electronic amplifiers[2] as well as in digital signal processing.[3] It is one of the fundamental issues addressed by control theory.[4][5][6]

Parasitic oscillation is undesirable for several reasons. The oscillations may be coupled into other circuits or radiate as radio waves, causing electromagnetic interference (EMI) to other devices. In audio systems, parasitic oscillations can sometimes be heard as annoying sounds in the speakers or earphones. The oscillations waste power and may cause undesirable heating. For example, an audio power amplifier that goes into parasitic oscillation may generate enough power to damage connected speakers. A circuit that is oscillating will not amplify linearly, so desired signals passing through the stage will be distorted. In digital circuits, parasitic oscillations may only occur on particular logic transitions and may result in erratic operation of subsequent stages; for example, a counter stage may see many spurious pulses and count erratically.

  1. ^ Whitaker, Jerry C. (2005). The electronics handbook. CRC Press. p. 404. ISBN 978-0-8493-1889-4.
  2. ^ Weber, Gerald (1994). A Desktop Reference of Hip Vintage Guitar Amps. Hal Leonard. p. 220. ISBN 978-0-9641060-0-0.
  3. ^ Wanhammar, Lars (1999). DSP integrated circuits. Academic Press. p. 188. ISBN 978-0-12-734530-7.
  4. ^ Richard R Spencer & Ghausi MS (2003). Introduction to electronic circuit design. Upper Saddle River NJ: Prentice Hall/Pearson Education. pp. 661. ISBN 0-201-36183-3. http://worldcat.org/isbn/0-201-36183-3.
  5. ^ Araki, M., PID Control, http://www.eolss.net/ebooks/Sample%20Chapters/C18/E6-43-03-03.pdf
  6. ^ P. Horowitz & W. Hill The Art of Electronics Cambridge University Press (1980) Chapter 3, relating to operational amplifiers.