Subthreshold conduction

About: Subthreshold conduction is a research topic. Over the lifetime, 6343 publications have been published within this topic receiving 131957 citations. The topic is also known as: Subthreshold leakage.

A physical and scalable I-V model in BSIM3v3 for analog/digital circuit simulation

Abstract: A new physical and continuous BSIM (Berkeley Short-Channel IGFET Model) I-V model in BSIM3v3 is presented for circuit simulation. Including the major physical effects in state-of-the art MOS devices, the model describes current characteristics from subthreshold to strong inversion as well as from the linear to the saturation operating regions with a single I-V expression, and guarantees the continuities of I/sub ds/, conductances and their derivatives throughout all V/sub gs/, V/sub ds/, and T/sub bs/, bias conditions. Compared with the previous BSIM models, the improved model continuity enhances the convergence property of the circuit simulators. Furthermore, the model accuracy has also been enhanced by including the dependencies of geometry and bias of parasitic series resistances, narrow width, bulk charge, and DIBL effects. The new model has the extensive built-in dependencies of important dimensional and processing parameters (e.g., channel length, width, gate oxide thickness, junction depth, substrate doping concentration, etc.). It allows users to accurately describe the MOSFET characteristics over a wide range of channel lengths and widths for various technologies, and is attractive for statistical modeling. The model has been implemented in the circuit simulators such as Spectre, Hspice, SmartSpice, Spice3e2, and so on.

Printed subthreshold organic transistors operating at high gain and ultralow power.

Abstract: Overcoming the trade-offs among power consumption, fabrication cost, and signal amplification has been a long-standing issue for wearable electronics. We report a high-gain, fully inkjet-printed Schottky barrier organic thin-film transistor amplifier circuit. The transistor signal amplification efficiency is 38.2 siemens per ampere, which is near the theoretical thermionic limit, with an ultralow power consumption of 60 decibels and noise voltage of <0.3 microvolt per hertz1/2 at 100 hertz.

Understanding DC Behavior of Subthreshold CMOS Logic Through Closed-Form Analysis

Abstract: In this paper, the DC behavior of subthreshold CMOS logic is analyzed in a closed form for the first time in the literature. To this aim, simplified large-signal and small-signal models of MOS transistors in subthreshold region are first developed. After replacing transistors with these equivalent models, analysis of the main DC parameters of CMOS logic gates is presented. In particular, the change in the DC characteristics shape due to operation at ultra-low voltages is analyzed in detail, evaluating analytically the degradation in the logic swing, the symmetry and the steepness of the transition region, as well as the change in the unity-gain points position. The resulting expressions permit to gain an insight into the basic dependence of DC behavior on design and device parameters. The noise margin is explicitly evaluated and modeled with a very simple expression. Interestingly, analysis shows that the noise margin deviates from the ideal half-swing value by an amount that linearly depends on the logarithm of the pn -ratio. Analysis permits to evaluate the minimum supply voltage that ensures correct operation of CMOS logic (i.e., positive noise margin). Previously proposed rule of thumbs to evaluate minimum voltage are also theoretically justified. Moreover, the impact of pMOS/nMOS unbalancing on DC characteristics is analyzed from a design perspective. Considerations on the impact of process/voltage/temperature variations are also introduced. Results are validated through extensive simulations in a 65-nm CMOS technology.

Effect of Gate Leakage in the Subthreshold Characteristics of AlGaN/GaN HEMTs

Abstract: This letter studies the effect of gate leakage on the subthreshold slope and ON/OFF current ratio of AlGaN/GaN high-electron mobility transistors (HEMTs). We found a strong correlation between the gate leakage current and the transistor subthreshold characteristics: the lower the gate leakage, the higher the ON/OFF ratio and the steeper the subthreshold slope. To improve the subthreshold characteristics in GaN HEMTs, the gate leakage current was reduced with an O2 plasma treatment prior to the gate metallization. The O2 plasma treatment effectively reduces the gate leakage current by more than four orders of magnitude, it increases the ON/OFF ratio to more than seven orders of magnitude and the improved AlGaN/GaN HEMT shows a nearly ideal subthreshold slope of 64 mV/dec.

Noise in Integrate-and-Fire Neurons: From Stochastic Input to Escape Rates

Abstract: We analyze the effect of noise in integrate-and-fire neurons driven by time-dependent input and compare the diffusion approximation for the membrane potential to escape noise. It is shown that for time-dependent subthreshold input, diffusive noise can be replaced by escape noise with a hazard function that has a gaussian dependence on the distance between the (noise-free) membrane voltage and threshold. The approximation is improved if we add to the hazard function a probability current proportional to the derivative of the voltage. Stochastic resonance in response to periodic input occurs in both noise models and exhibits similar characteristics.