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Noise Sources
Published in Antoni Rogalski, Zbigniew Bielecki, Detection of Optical Signals, 2022
Antoni Rogalski, Zbigniew Bielecki
Physical noise processes are inherent in any natural process or electronic component such as the detectors or transistors. Some noise processes can be derived and expressed in rigorous mathematical terminology, whereas other processes are not well understood. In detectors of light, the physical noise sources include Johnson (thermal or Nyquist) noise, shot noise, temperature-fluctuation noise and generation–recombination (g-r) noise. Johnson noise results from random charge movement due to thermal agitation in a conductor. Shot noise arises from the statistical occurrence of discrete events, such as when charges cross a bandgap potential barrier in a semiconductor. Generation-recombination noise occurs when electron-hole pairs (with finite carrier lifetime) are generated or recombined in a semiconductor. From the other side, the noise with 1/f (f is electrical frequency) fractal power spectrum defies physical explanation. 1/f noise is present in detectors, electronic circuits, flow processes such as natural rivers and traffic, biological processes and music.
Noise in Semiconductor Devices
Published in Bogdan M. Wilamowski, J. David Irwin, Fundamentals of Industrial Electronics, 2018
Alicja Konczakowska, Bogdan M. Wilamowski
Generation-recombination noise is caused by the fluctuation of number of carriers due to existence of the generation-recombination centers. Variation of number of carriers leads to changes of device conductance. This type of noise is a function of both temperature and biasing conditions. The spectral density function of the generation-recombination noise is described by () Sg−r(f)N2=(ΔN¯)2N2⋅4τ1+(2πf⋅τ)2
Noise Measurement
Published in John G. Webster, Halit Eren, Measurement, Instrumentation, and Sensors Handbook, 2017
Generation–recombination noise is a semiconductor that is generated by the random fluctuation of free-carrier densities caused by spontaneous fluctuations in the generation, recombination, and trapping rates [7]. In BJTs, it occurs in the base region at low temperatures. The generation–recombination gives rise to fluctuations in the base-spreading resistances that are converted into a noise voltage due to the flow of a base current. In junction FETs, it occurs in the channel at low temperatures. Generation–recombination causes fluctuations of the carrier density in the channel, which gives rise to a noise voltage when a drain current flows. In silicon junction FETs, the effect occurs below 100 K. In germanium junction FETs, it occurs at lower temperatures. The effect does not occur in metal–oxide–semiconductor field-effect transistors (MOSFETs).
TCAD Investigation for Dual-Gate MISHEMT with Improved Linearity and Current Collapse for LNAs
Published in IETE Technical Review, 2022
Preeti Singh, Vandana Kumari, Manoj Saxena, Mridula Gupta
The influence of asymmetric gate workfunction on the gate voltage swing has been explored in Figure 8(a). GVS is nearly same for case II with different gate metals for gate G2 (i.e., variation with ϕm2) as clearly evident in Figure 8(a). However, positive shift in gmpeak has been observed with increasing VGS values. Evaluation of minimum noise figure is another crucial parameter for LNA. Figure 8(b) depicts the variation of minimum noise figure for DG-MISHEMT with gate biasing configured as per case II and distance between the two gates (LGG) is 100 nm. It is clearly shown that as gate workfunction for gate G2 (ϕm2) increased to 5.2 eV, the NFmin changes only slightly to 2.24 dB at 50 GHz as compared with NFmin of 2.03 dB for device with low gate workfunction ϕm2 of 4.1 eV. This is due to the fact that with enhanced gate workfunction value for ϕm2, generation-recombination noise component also rises and leads to increased NFmin (∼10%) at 50 GHz.