Showing papers on "Subthreshold conduction published in 1975"

Device design considerations for ion implanted n-channel MOSFETs

Abstract: Device design considerations are presented for ion implanted, n-channel, polysilicon gate, enhancement-mode MOSFETs for dynamic switching applications. A shallow channel implant is used to raise the magnitude of the gate threshold voltage while also maintaining a low substrate sensitivity (i.e., without substantially increasing the dependence of the threshold voltage on the source-to-substrate "backgate" bias). Design trade-offs between channel implantation energy and dose and substrate bias were examined using both computer analyses and experimental devices. The design objective was to identify the combination of these three parameter values that gives both a low substrate sensitivitya nd a steep subthreshold conduction characteristic under the conditions of a gate threshold voltage of 1 V and a substrate bias range of 0 to -1 V. One-dimensional and two-dimensional computer analyses were performed to predict the effect of the device parameters on the electrical characteristics. MOSFETs were then fabricated to investigate the extremes of the design parameter range, and the experimental and predicted device characteristics were compared. An enclosed device structure proved particularly useful in evaluating the subthreshold characteristic at very low values of drain current.

Influence of the channel width on the threshold voltage modulation in m.o.s.f.e.t.s

Abstract: The threshold vollage of an m.o.s. field-effect transistor is modulated by the source-to-substrate reverse bias. In the letter, the theory for long- and short-channel transistors is extended to include the influence of the channel width. The result is an analytical expression for the threshold voltage as a function of geometry and bias that agrees well with experimental data.

Subthreshold slope for insulated gate field-effect transistors

Abstract: An explicit expression has been derived for the subthreshold slope of an insulated gate field-effect transistor. This expression is used to explore the influence of surface band-bending, gate insulator thickness, substrate doping, substrate bias, and temperature.

Noise in MOS bucket-brigade devices

Abstract: Previous calculations of noise in bucket-brigade devices (BBD's) have ignored subthreshold leakage current even though BBD's operate in the subthreshold region over most of their useful frequency range. In this work, subthreshold leakage is included in the calculation, but surprisingly, it makes little difference in the end result. The noise spectrum in p-channel BBD's is measured and agrees well with the calculated noise spectrum which includes the effects of correlation between noise packets, imperfect charge transfer efficiency, and output circuitry.

Capacitive means for controlling threshold voltages in insulated gate field effect transistor circuits

Abstract: Circuit means for eliminating the effect of excessive threshold voltages in insulated gate field effect transistor inverter-type circuits utilizes capacitor pull-up. Capacitors are selectively coupled from various phased voltage outputs of a multi-phase voltage supply to the driver-gate of various field effect transistors to provide increased voltage during voltage pulses of the phase involved. A voltage between the threshold voltage and a required minimum noise margin is thereby added to the driver-gate input signal to overcome the threshold voltage effect. This circuit means is particularly useful in dynamic circuits such as multiphase shift registers and bipolar-to-high voltage field effect transistor coupled circuits.

Subthreshold membrane currents in slowly adapting stretch receptor neurone of lobster.

Abstract: IN the slowly adapting stretch receptor neurone of lobster, application of tetrodotoxin (TTX) causes a simultaneous hyperpolarisation and decrease in input resistance1 These effects have been attributed to a possible increase in potassium conductance They could, however, be explained by elimination of a subthreshold steady-state sodium conductance which, in this case, might underlie the cell's repetitive mode of firing2 To examine this possibility, we made a voltage clamp study of the subthreshold steady-state membrane currents of the slowly adapting stretch receptor neurone of lobster The results indicate the existence of a subthreshold steady-state Na current which to a large extent seems to be balanced by a leak type current

Temperature dependence of the subthreshold velocity/field characteristic for epitaxial InP

Abstract: The subthreshold electron-drift-velocity/field characteristic for epitaxial InP has been measured over the temperature range 118?446 K. The threshold field of H-shaped devices is found to increase from 8 to 12.3 kV/cm and the peak velocity to decrease monotonically from 3.3×107 to 1.9×107 cm/s over this temperature interval.

Plasma Fluctuations Induced by Subthreshold Pump Fields

Abstract: We present in this work three equivalent methods to calculate stable plasma density fluctuations induced by a uniform oscillating electric field near the plasma frequency, somewhat below threshold ...

The phase of supernormal excitation in relation to the strength of subthreshold stimuli

Abstract: The presence of supernormal excitation was confirmed repeatedly in all 10 cases following cardiac surgery By the stimulation of minimum subthreshold impulses capable of originating ventricular responses, the supernormal excitation was limited only at the descending limb of T wave The duration lasted only 002 sec at the minimum subthreshold stimuli But the higher subthreshold stimuli produced the longer duration of supernormal excitation phase The duration of the excitation phase prolonged towards the following R wave, hardly extending towards the preceding R wave, with the increase of subthreshold stimuli