What is the threshold voltage?

What is the threshold voltage?

What is Threshold Voltage? A Key Parameter in MOSFET Operation Explained
The threshold voltage, also known as the “threshold” or “Vth”, is a critical parameter in the operation of a metal-oxide-semiconductor (MOS) transistor. It is the voltage that must be applied to the gate of the MOS transistor to turn it on and allow a significant current to flow between the source and drain.

Threshold voltage in CMOS
The MOS transistor’s switching properties, including its on-state resistance, transconductance, and turn-on delay time, are determined by the threshold voltage. The amount of doping in the source and drain regions, the thickness of the oxide layer, and the kind of gate material all have an impact on the threshold voltage. The threshold voltage is a key factor in defining the point in digital circuits where the MOS transistor flips from the off state to the on state. In order to guarantee that the MOS transistor can function dependably under a variety of process, voltage, and temperature fluctuations, this threshold point is frequently established at a specified voltage value.

What is the threshold voltage in a diode?
Diodes require a minimum threshold voltage, or Vth, between the anode and cathode in order for current to flow. This voltage is typically approximately 0.7V. No current will pass through the diode if the anode voltage is not at least Vth larger than the cathode voltage.

Why does threshold voltage increase?
When a back bias is applied, the threshold voltage rises. A larger depletion region is produced by a positive bias on the substrate, which also helps keep the gate charge in check. As a result, there are fewer electrons present in the inversion layer.

Does threshold voltage change with temperature?
As temperature rises, the threshold voltage decreases, and the subthreshold leakage current increases exponentially with an increase in temperature.

Is the threshold voltage and knee voltage the same?
A significant forward current must start flowing across the diode before a potential difference equal to the barrier potential is reached at room temperature. This value is often referred to as the “(V th)” threshold voltage, “cut-in voltage,” or “knee voltage.”

10 Examples of Difference Threshold
Vision: Subtle shifts of coloring, perceivable to the naked eye, are known as visual thresholds. If two colors are close enough in hue and value, they might not be discernible to the human eye. The minimally perceptible difference between these two similar colors is known as the difference threshold.

Taste: In terms of taste, we can explore the smallest detectable change in sweetness or sourness. So, the minimum difference in the quantity of sugar in the cake a person can taste is known as the difference threshold.

Smell: The minutest difference in scent intensity is referred to as the smell threshold. The smallest detectable change in the amount of an aroma or fragrance is known as the difference threshold.

Hearing: Similarly, when it comes to sound intensity or pitch, we can assess the minimum amount of change that one can sense between two similar sounds. So, the minimum change in the TV volume a person can perceive is known as the hearing difference threshold.

Touch: The touch threshold is the slightest detectable variation in temperature. If, for example, a person feels a difference in temperature when touching two objects, the minimum perceivable change in heat between them is known as the touch threshold.

Weight: The smallest variation in weight a person can detect between two objects is known as the “weight difference threshold.” In other words, if someone holds up two pens of differing weights and is asked to differentiate them, they may not be capable until there’s an ample difference.

Pressure: Likewise, the pressure threshold is the minimum detectable difference in pressure between two stimuli. To put it another way, if a person tries to identify variations in pressure between two objects, they may not be able to detect any until the amount of pressure reaches an identifiable level.

Luminance: The luminosity difference threshold is the minimum detectable change in brightness between two stimuli. For instance, minuscule fluctuations in light intensity are enough for humans to differentiate between two lighting sources.

Size: The size difference threshold is the minimum size change between two objects that a person can detect. So, holding two boxes of different sizes in each hand, the person may not be able to tell the difference until one of them is much bigger than the other.

Time: The temporal difference threshold is the minimum amount of time between two successive events that a person can perceive. For instance, if two events are presented in quick succession, the person may not be able to tell the difference until there is a considerable passage of time between them.