Low-Frequency Noise Phenomena in Switched MOSFETs

Abstract

Abstract-In small-area MOSFETs widely used in analog and RF circuit design, low-frequency (LF) noise behavior is increasingly dominated by single-electron effects. In this paper, we review the limitations of current compact noise models which do not model such single-electron effects. We present measurement results that illustrate typical LF noise behavior in small-area MOSFETs, and a model based on Shockley-Read-Hall statistics to explain the behavior. Finally, we treat practical examples that illustrate the relevance of these effects to analog circuit design. To the analog circuit designer, awareness of these single-electron noise phenomena is crucial if optimal circuits are to be designed, especially since the effects can aid in low-noise circuit design if used properly, while they may be detrimental to performance if inadvertently applied.Index Terms-CMOS, flicker noise, large-signal excitation, lowfrequency noise, low-noise circuit design, MOSFET, noise reduction, RTS noise, switched biasing, 1 noise.

Electrical noise in Circular Gate Tunnel FET in presence of interface traps

“…A few works have been reported and modeled the impact of noise on TFETs [16][17][18], but extensive studies on various structures of TFETs are yet to be done. Analysis of low frequency noise in MOSFET owes its basis to the two models of fluctuation theory: (a) fluctuating free carrier based McWhorter's fluctuation theory (1955) [19], and (b) mobility fluctuation based Hooge's fluctuation theory (1962) [20,21]. In n-TFETs, the carriers are generated by Band-to-Band Tunneling from source to channel at the tunnel junction, which supposedly is in accordance with both the theories, as mobility fluctuations are correlated to fluctuations in free carriers [19].…”

Analysis of Low-Frequency Noise in Switched MOSFET Circuits: Revisited and Clarified

“…On the other hand, the real noise reduction effect is observed at frequencies lower than the switching frequency, and this is the region where the incorrect PSD computed in [12] differs from the actual, corrected result which shows larger noise reduction at lower frequencies. We note that, since the corner frequency of the correct switched PSD in (18) is independent of , the integration operation in (22) does not change the location of the corner. The resulting noise time-averaged PSD retains the same form as the PSD in the single trap case, representing the maximum achievable noise reduction due to bias switching under idealized conditions.…”

“…4 (asterisk marks) is the noise spectrum one would obtain without periodic switching of the input voltage. In other words, if one replaces in (22) with the Lorentzian PSD in (20), the result of the integration is a curve that decays with a constant 10 dB/decade slope. The second curve (triangular marks) is 3 dB below the first curve, obtained with the stationary model for the switched input case with a 50% duty cycle.…”

“…Additionally, the required relationships of and , both in the on and off-state, are not guaranteed to be satisfied in realistic systems. The equality assumption of the transition rates in the on-state, , has no sound physical motivation and the condition that is only partially backed up by measurements results [22], [23].…”

Modeling and simulation of noise in transistors under large-signal condition

“…The first approach is in principle to be preferred in terms of physical model consistency, though the implementation is usually confined to very simple devices and/or idealized structures: an example is the diode LS noise model described in [50], [51], which we are currently extending to the bipolar transistor case. Other possible system oriented approaches are those exploited for the modeling of the reduction in low-frequency noise experimentally observed in MOSFETs under switched operation [53]- [55].…”