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Member of: Design Principles

General noise notes and noise of passive components.

White Noise

  • Noise power is constant across all frequency bands. or Any point in time is completely uncorrelated with any other point in time.
  • There are 2 types of white noise: Shot noise and Flicker noise.

Shot Noise

  • Comes from a source of carriers
  • This noise models the variation in generation and arrival of carriers.
  • This is present in the diode, BJT, and Vacuum tubes (Devices with a depletion region where carriers see no noise, thus not in MOSFETs.)

Thermal Noise

  • This noise models the variation transport of carriers in a channel.
  • This is present in the resistor, MOSFET, and JFET (Devices with a channel that can fluctuate with temperature.)

Flicker Noise (Pink Noise)

  • Largest noise power is in lower frequencies, or low frequency noise is well correlated, or this is slowly varying noise.

Passive Devices

  • Resistor has thermal noise
    • \frac{ \bar{i_n^2} }{\Delta f} = \frac{ 4kT}{ R } and \frac{ \bar{v_n^2} }{\Delta f} = 4kT R
    • k is Boltzmann’s constant in joules per kelvin (1.380 6505(24)×10−23)
    • T the Temperature in Kelvins
    • The units are A2/Hz and V2/Hz
  • Capacitor has no intrinsic noise
    • However, capacitor will integrate any noise from series resistance.
    • The noise power when the capacitor is charging is then \frac{ kT }{C} (V2)

See Also:

Backrefs:

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Last edited by DrLock. Originally by DrLock.