Noise, Low‐Frequency

Abstract

Low‐frequency noise, containing fluctuations of current or voltage with frequency components below 10 kHz, is mainly fundamental 1/ f noise and sometimes nonfundamental 1/ f noise. In addition, shot noise, generation–recombination (GR) noise, and thermal noise, which are important at higher frequencies, also extend to the low‐frequency domain. All theses forms of electronic noise, are characterized by the mean squared current fluctuation (( δI ) 2 ) [or (( δV ) 2 ≡RMS δV ) 2 for voltage], measured in series with (or across) the device or sample under test, when a constant voltage (current) is applied, except for thermal noise, which is present even in thermal equilibrium, with no bias applied.

1∕f Performance Limits of Scanning Tunneling Microscopes

“…Therefore, the fractional fluctuations in phonon emission rate are equal to the fractional fluctuations in relaxation rate: 5 sx/x = 5 sr/r-According to the general quantum 1/f formula, F"^ 5 r (/) = laAJf, where a = e^/hc is the fine structure constant and A = 2(AJ/ec)^/37i is the quantum 1/f effect in any physical process rate F [2], [3]. The current discontinuity AJ in the Ampere-Maxwell equation equals the discontinuity AdP/dt in the rate of the crystal dipole moment change dP/dt.…”

“…The largest contribution will not come from the main resonator 1/n factor, but from the 1/n factor corresponding to the high-frequency thermal modes that have n close to 1. Furthermore, n is the number of thermal phonons at the frequency <C0eff > of the quartz, which we set equal to unity [2], [3]. Each coherence volume e^ of the quartz crystal has independent dissipation fluctuation, with e being the phonon coherence length.…”

Piezoelectric quantum 1/f noise in AlGaN HFETs and reliability

“…There are as many types of quantum 1/f noise [1]- [5], as there are systems of massless infraquanta with infrareddivergent coupling to the current carriers. Each of these types has a conventional and coherent part, corresponding to terms in the hamiltonian that are proportional with the first and second power of the number of carriers defining the current, respectively.…”

Noise in THz detectors and generators

“…Because the dark current is a factor in optimizing device performance, we will investigate the noise associated with this current. The noise is described by the conventional quantum 1/f effect [4], [6], [12] which describes the fundamental fluctuations in the physical cross sections and process rates that generate the dark current. The calculation of the 1/f noise is then compared to experimental data from Jutao Jiang (and Manijeh Razeghi) [13].…”

“…According to quantum 1/f noise theory, [4], [6], [12], due to minute bremsstrahlung energy losses in scattering processes, the scattered current will exhibit fractional quantum fluctuations with the same (actually twice) spectral density as the number of the emitted bremsstrahlung photons. The later is known to be inversely proportional to the frequency.…”