Showing papers on "Subthreshold conduction published in 1977"

Spatial properties of binocular neurones in the human visual system.

Abstract: The spatial properties of human binocular mechanisms were investigated using the technique of subthreshold summation. Isolation of binocular mechanisms was achieved by means of interocular stimulus presentation. The contrast detection threshold for a sinusoidal test grating viewed by one eye was found to be reduced by a subthreshold grating of the same spatial frequency and orientation seen by the other eye. The interaction between the gratings was approximately linear. Threshold increased as the spatial frequencies or orientations of test and subthreshold gratings were made increasingly different. Spatial stimulus specificities measured in this way were as great for interocular presentation as for simultaneous monocular presentation. The results suggest that human contrast sensitivity for gratings may depend upon binocularly-activated neurones similar to those found in cat and monkey visual cortex.

A new approach to the theory and modeling of insulated-gate field-effect transistors

Abstract: Consideration of basic charge relationships in the IGFET has led to a new formulation of the theory of the device which allows model characterization in a more general manner, and with greater accuracy, than previously achieved. The contribution of the mobile channel charge to the silicon surface potential, which is believed to have a significant influence on the device characteristics, is taken into account in this approach. Accurate device modeling is achieved over a very wide range of operation, extending from weak channel (subthreshold) to high level channel conditions. An important feature of the model is that it is expressed in terms of a constant effective channel mobility. Further, the current and charge relationships involved take the form of a single set of analytic closed-form expressions in terms of the terminal voltages for all conditions of device operation, and are thus appropriate for CAD implementation. The scope and accuracy of this approach to IGFET modeling are demonstrated by comparisons between measured and theoretical dc and small-signal characteristics for sample metal and silicon gate devices.

On the problem of displacement threshold determination in irradiated metals: subthreshold effects and recovery spectrum

Abstract: A method for determining the true threshold energy for creating Frenkel pairs in an irradiated metal is proposed. In this method, occasional subthreshold phenomena are separated from the direct displacement process by investigating the stage I annealing spectrum after bombardment with particles having energies close to the suspected threshold.

On subthreshold solutions of the Hodgkin-Huxley equations.

Abstract: Subthreshold solutions of the Hodgkin-Huxley equations are considered here by means of the linearized forms of these equations. An asymptotic theory is obtained, based on dimensional analysis and scaling arguments. Explicit expressions for the crest speed are obtained and are shown to be in good agreement with experiment, with computation, and with an exact asymptotic value which is also obtained here.

Measurement of the Uranium-238 Subthreshold Fission Cross Section for Incident Neutron Energies Between 0.6 and 100 keV

Abstract: We have measured the neutron-induced 238U subthreshold fission cross section in the neutron energy range between 06 and 100 keV A total of 28 fission clusters were identified The well-known clus

A short channel MOSFET model

Abstract: The MOSFET equivalent circuit model described incorporates short channel and temperature effects. It includes expressions for the device current in the subthreshold, triode and saturation regions and uses a field dependent mobility and a drain voltage dependent threshold voltage. The drain current-voltage characteristic and its first derivative are continuous in all regions. Relationships for the gate-source and gate-drain capacitances are derived as a function of the device potentials using a field dependent mobility. Using the closed form expressions of this model, simulations were performed for micron long devices having uniform and ion-implanted channel profiles and compared with data at room, above room and liquid nitrogen temperature.

Ion implanted MOS transistors

Abstract: A review of the principal features of ion implanted transistors is presented. A detailed analysis of the threshold voltage shift is given, with emphasis directed towards dose and energy effects. Analytical expressions are derived for enhancement mode devices and compared with numerical solutions; the effect of the implantation on subthreshold currents is described. Some aspects of depletion mode transistors are treated.

Evaluation of the threshold voltage for short-channel MOSFET's

Abstract: It has been well known that in a long‐channel MOSFET, the experimental value of the threshold voltage obtained by the square‐root extrapolation method in the saturation region agrees well with the theoretical criterion. In a short‐channel MOSFET, the so‐determined threshold voltage depends on the drain voltage because of the drain current dependence on the drain voltage VDS. In this letter, a new method to determine the threshold voltage for VDS=0 V will be discussed.