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ABSTRACT: This paper presents a study on 1/f noise in MOSFETs under large-signal (LS) operation, which is important in CMOS analog and RF integrated circuits. The flicker noise is modeled with noise sources as a perturbation in the semiconductor equations employing McWhorter's oxide-trapping model and Hooge's empirical 1/f noise model. Numerical results are shown for 1/f noise in the MOSFET in both small-signal operation and periodic LS operation. It is shown that McWhorter's model does not give any significant 1/f noise reduction when the oxide traps are distributed uniformly in energy and space. In contrast, Hooge's model gives almost 6-dB 1/f noise reduction as the gate off-voltage decreases below the threshold voltage. It is found that both models fall short of explaining the noise reduction by more than 6 dB, as observed experimentally in the literature. However, when only one active oxide trap is considered, which generates random telegraph signal (RTS) in drain current, the LS operation gives more than 6-dB low-frequency RTS noise reduction.
IEEE Transactions on Electron Devices 06/2010; · 2.32 Impact Factor
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ABSTRACT: We propose a statistical method to predict the dark random readout noise in CMOS image sensors. First, we calculate the dark random noise originated from oxide traps present in the source-follower MOSFET. Statistical variation in the dark noise is associated with the random variation of the oxide defects in the CMOS image sensor cells in both the energy and space domain. Considering the effect of the correlated double sampling, we define the dark random noise as the standard deviation in the time domain and analyze the effect of the MOSFET width and length variations and temperature on its dark random noise.
Simulation of Semiconductor Processes and Devices, 2008. SISPAD 2008. International Conference on; 10/2008
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ABSTRACT: Modeling capabilities and considerations to achieve a unified reliability model (URM) are addressed. The causes of the trap generation and their effects on the device characteristics serve the unified reliability model. A strategy taken in the SNU group based on the CLESICO system is introduced, where the hydrogen transport and trapping in the gate dielectric to form active carrier trapping sites and their effects on the device characteristics such as the current degradation are treated in a systematic and statistical manner. The treatment of the discrete nature of the trapped charges to model the RTS and 1/f noises are also introduced.
Simulation of Semiconductor Processes and Devices, 2008. SISPAD 2008. International Conference on; 10/2008
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ABSTRACT: 1/f noise in MOSFETs under large-signal excitation, which is important in CMOS analog and RF circuits, is modeled as a perturbation
in the semiconductor equations employing the oxide-trapping model. The oxide-trapping model for a MOSFET in periodic large-signal
operation shows that 1/f noise reduces more than the small-signal noise model predicts as the gate OFF voltage decreases further below the threshold
voltage.
11/2007: pages 89-92;
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ABSTRACT: This paper presents the governing equations of the Green’s functions for the short-circuit terminal noise currents of semiconductor devices under the drift-diffusion scheme. Using these equations, the Nyquist theorem is derived for multiterminal bipolar semiconductor devices at nonzero frequencies with generation-recombination processes considered. It is explicitly shown that generation-recombination noise sources play an essential role in canceling out part of terminal noise contributions from diffusion noise sources to finally obtain the equilibrium thermal noise.
Journal of Applied Physics 11/2007; · 2.17 Impact Factor
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ABSTRACT: A general TCAD framework for the large-signal (LS) noise analysis of RF CMOS circuits has been developed employing an efficient preconditioner for generalized minimal residual (GMRES) method. In this framework the influence of the noise sources inside the devices on the output noise of the circuit is calculated using the conversion Green's function (CGF) technique. We expect that the newly-developed TCAD framework can provide a physics-based and efficient LS noise analysis under a mixed device-circuit environment. As an application, noise behaviors of a single-balanced down-conversion mixer has been simulated using this framework.
Simulation of Semiconductor Processes and Devices, 2005. SISPAD 2005. International Conference on; 10/2005
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ABSTRACT: An analytical formula of excessive thermal noise in short-channel MOSFETs at saturation is developed following the approach used for GaAs JFET or MESFET by Statz, Haus, and Pucel. It is taken into account that the noise generated in the velocity saturation region comes from randomly generated dipole layers which propagate toward the drain contact without relaxation. Simulation of the derived formula shows that the velocity saturation region plays a crucial role in determining excessive thermal noise in short-channel MOSFETs. The proposed thermal noise formula is confirmed by the comparison to the published experimental results of high-frequency noise in the short-channel nMOSFET of channel length 0.7 μm at saturation.
Solid-State Electronics. 44(11):2053-2057.
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ABSTRACT: We have derived an accurate noise current density equation for homogeneous semiconductors under a constant magnetic field with three noise source terms which are the thermal noise source term and the two excess noise source terms due to either carrier number fluctuation or carrier mobility fluctuation. Based on Hooge’s empirical relations for 1/f noise, the two excess noise source terms are shown to become equal to each other under zero magnetic field. Using the characteristic potential method and employing Hooge’s empirical relations for 1/f noise, we have derived the formulas for the short-circuit terminal 1/f noise and thermal noise currents and the open-circuit terminal 1/f noise and thermal noise voltages of multi-terminal homogeneous semiconductor resistors with arbitrarily-shaped 2-D geometries under a constant magnetic field. We have shown that the derived formulas can explain the measured 1/f noise and thermal noise of n-GaAs rectangularly-shaped Hall devices and n-GaAs Corbino disks under magnetic field from 0 to 8 T at room temperature. It is also shown that the magnetic field dependence of 1/f noise in bulk semiconductors should be explained by the number fluctuation model rather than by the mobility fluctuation model.
Solid-State Electronics. 48(5):641-654.
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ABSTRACT: A 1/f trapping noise theory in Si nMOSFETs biased in weak inversion is presented. The explicit derivation starts from the diffusion current equation which dominates the drift current term when MOSFET is in weak inversion. It is shown that the formula is consistent with the existing Reimbold's 1/f trapping noise theory.
Solid-State Electronics. 43(12):2111-2113.
