The threshold voltage, commonly abbreviated as Vth, of a field-effect transistor (FET) is the minimum gate-to-source voltage VGS (th) that is needed to create a conducting path between the source and drain terminals. It is an important scaling factor to maintain power efficiency.

A stimulus from a sensory cell or another neuron depolarizes the target neuron to its threshold potential (−55 mV). Na+ channels in the axon hillock open, allowing positive ions to enter the cell (Figure 1).

One of the most important physical parameters of a MOSFET is its threshold voltage V th , defined as the gate voltage at which the device starts to turn on. The accurate modeling of threshold voltage is important to predict correct circuit behavior from a circuit simulator.

Chapter 7: MOS Field-Effect-Transistors

1. 7.4. Threshold voltage calculation. The threshold voltage equals the sum of the flatband voltage, twice the bulk potential and the voltage across the oxide due to the depletion layer charge, or:
2. 7.4. The substrate bias effect.

Threshold voltage. The threshold voltage, commonly abbreviated as Vth, of a field-effect transistor is the value of the gate–source voltage when the conducting channel just begins to connect the source and drain contacts of the transistor, allowing significant current to flow.

At circuit level, the threshold voltage can be reduced by increasing the potential of the channel for the same gate-source voltage. As the channel potential is the result of the gate, source, drain and bulk/body (back-gate) potential, playing with the latter three can effectively alter the threshold voltage.

[′thresh‚hōld ‚val·yü] (computer science) A point beyond which there is a change in the manner a program executes; in particular, an error rate above which the operating system shuts down the computer system on the assumption that a hardware failure has occurred. (control systems)

Threshold voltage is the voltage above which current increases very rapidly with applied voltage. Beyond threshold voltage, the resistance offered by the potential barrier is overcome by forward bias voltage, therefore, it is easy for charge carriers to cross the barrier.

approximately 0.7 V

The value of the threshold voltage is dependent from some physical parameters which characterize the MOSFET structure such as: the gate material, the thickness of oxide layer tox, substrate doping concentrations (density) NA, oxide –interface fixed charge concentrations (density) Nox, channel length L, channel width W …

The threshold voltage of an n-channel MOSFET can be increased by:

1. A. Increasing the channel dopant concentration.
2. B. Reducing the channel length.
3. C. Reducing the gate oxide thickness.
4. D. Reducing the channel dopant concentration.

Pinch off voltage: Pinch off voltage is the drain to source voltage after which the drain to source current becomes almost constant and JFET enters into saturation region and is defined only when gate to source voltage is zero.

SUBTHRESHOLD LEAKAGE CURRENT As temperature rises, the threshold voltage decreases and the subthreshold leakage current increases exponentially with increase in temperature. So this leakage becomes a severe problem in the case of devices operating at high temperatures.

Mobility and threshold voltage both decreases with temperature. But decrease in mobility means less drain current and slower device, whereas decrease in threshold voltage means increase in drain current and faster device.

Changes in temperature affected the amplitude of action potentials, measured as the voltage difference between the threshold and the peak, and their duration, measured as the width of the action potential at the threshold.

At room temperatures of 25°C or 78°F, there is negligible amount of minority carriers present in a reverse bias diode. When the surrounding temperature rises, it causes significant increase in minority carrier creation and as a result it causes a corresponding increase in leakage current.

In any electrical installation, some current will flow through the protective ground conductor to ground. But, if the insulation is old or damaged, the resistance is lower and substantial current may flow. Additionally, longer conductors have a higher capacitance, causing more leakage current.

It has been observed that the leakage current decreases with the temperature up to 80 °C. Above 80 °C, the leakage current increases with the temperature. The negative temperature dependence of leakage current with the activation energy +0.61 eV is due to the impact ionization.

The leakage current can be estimated as follows from the insulation resistance specification value and the rated voltage of the item using the formula I = V/R.

Leakage current is the current that flows through the protective ground conductor to ground. In the absence of a grounding connection, it is the current that could flow from any conductive part or the surface of non-conductive parts to ground if a conductive path was available (such as a human body).

Leakage Current Test (Line Leakage Test) This test is generally carried out at 100%-110% of the rated input voltage of the product under test. The maximum acceptable limit of a leakage current is generally 210 micro amperes.

An especially simple and effective option for reducing leakage current is to use a 4-conductor filter with a neutral conductor instead of a 3-conductor filter.

Patient leakage current is the leakage current that flows through a patient connected to an applied part or parts. • The patient auxiliary current is defined as the current which normally flows between parts of the applied part through the patient which is not intended to produce a physiological effect.

A typical method for the decrease in parasitic capacitor impedance is to augment the impedance along the path of leakage current. The coupled transformer featured with a galvanic isolation is the most representative to be widely employed either in AC circuit or DC circuit for suppressing the leakage current.