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S v contains both amplitude and phase components, but with oscillators the phase noise dominates except at frequencies far from the carrier and its harmonics. S v is directly observable on a spectrum analyzer, whereas S φ is only observable if the signal is first passed through a phase detector.
In signal processing, phase noise is the frequency-domain representation of random fluctuations in the phase of a waveform, corresponding to time-domain deviations from perfect periodicity . Generally speaking, radio-frequency engineers speak of the phase noise of an oscillator, whereas digital-system engineers work with the jitter of a clock.
Leeson's equation is an empirical expression that describes an oscillator's phase noise spectrum. Leeson's expression [ 1 ] for single-sideband (SSB) phase noise in dBc/Hz (decibels relative to output level per hertz) and augmented for flicker noise : [ 2 ]
The more phase noise the oscillator exhibits, the wider the bandwidth of each harmonic. Phase noise is a noise in the phase of the signal. Consider the following noise free signal: v(t) = Acos(2πf 0 t). Phase noise is added to this signal by adding a stochastic process represented by φ to the signal as follows: v(t) = Acos(2πf 0 t + φ(t)).
The low frequency flicker noise affects the phase noise because the flicker noise is heterodyned to the oscillator output frequency due to the non-linear transfer function of active devices. The effect of flicker noise can be reduced with negative feedback that linearizes the transfer function (for example, emitter degeneration).
Generation-recombination noise, in semiconductor devices; Oscillator phase noise, random fluctuations of the phase of an oscillator; Barkhausen effect or Barkhausen noise, in the strength of a ferromagnet; Spectral splatter or switch noise, caused by on/off transmitter switching; Ground noise, appearing at the ground terminal of audio equipment
Phase portrait of damped oscillator, with increasing damping strength. All real-world oscillator systems are thermodynamically irreversible. This means there are dissipative processes such as friction or electrical resistance which continually convert some of the energy stored in the oscillator into heat in the environment. This is called damping.
Phase noise of −150 dBc at 10 kHz from 10 MHz is now available, a level that is generally only needed for radio frequency (RF) applications. MEMS oscillators are now available with integrated jitter under 1.0 picosecond, measured from 12 kHz to 20 MHz, a level that is normally required for high speed serial data links, such as SONET and SyncE ...