10.2. I-V Characteristic Exploration

So, here what you see it is that, suppose if we apply the voltage here V and also we apply V keeping body and source they are connected. So, we call this is V and this is DS V the current it will be of course, we do have insulator. So, through this terminal there will not be any current, but then there will be a current flow.

In this chunk, we discuss the application of voltages Vgs and Vds in a device setup. When voltage is applied, it creates conditions for current to flow through the device. Even though there is an insulator that would typically block current at one terminal, a flow can occur in the right environment. This is foundational for understanding circuit behavior, especially how currents interact with voltage in devices.

Think of it like water flowing through a pipe. If you turn on a faucet (apply voltage), water (current) starts flowing even if some sections of the pipe (insulator) are blocked. The key is creating the right conditions (applying the correct voltages) for water to flow.

So, this I it is flowing here. And, of course, this current it is carried by electrons. So, these electrons are really moving from left to right by this field or by this voltage, you may say this is lateral field. So, we can say this vertical field it is getting created by Vgs, which is changing the concentration of the electron; on the other hand, the horizontal field getting created by Vds, which is helping for the movement of the electron from left to right.

Here, we explore how the current (I) is essentially flow of electrons within the device. The applied voltage creates electric fields - a vertical field from Vgs modifies the electron density, while a horizontal field from Vds drives electrons along a specific path (left to right). Understanding how these fields interact is crucial for electrical engineers in predicting how a device will respond to different voltages.

Imagine a playground slide (the vertical field) where kids (electrons) are waiting at the top (increased density). When they push down the slide (horizontal field), it helps them move quickly to the bottom (current flow). The combination of forces from both fields is essential to get the kids moving!

So, note that these electrons are coming from this side. So, that is why you call this is source and it is getting drained to this terminal that is why you call drain. Now, it is very clear that why you call this is drain and source.

This chunk clarifies the terms 'source' and 'drain' used in electronic devices. Electrons originate from the 'source' terminal and flow towards the 'drain' terminal, a crucial concept for understanding how devices operate. Knowing this can help students visualize the internal workings of transistors and similar components.

Imagine a river (the source) flowing into a lake (the drain). The water is similar to the electrons – it's coming from one place and getting collected in another, illustrating how current flows through a circuit.

So, this current flow I it is a strong function of this Vgs, Vds and also it is a strong function of the spacing from here to here, namely the length of the device. It is also a strong function of the width of the device and also it is strong function of the device parameter, which includes the thickness of this oxide, referred as t, the dielectric constant here of this ox portion referred as ε, and of course, the mobility of the electrons in the channel region.

This section highlights the various parameters that influence the current (I) flowing through a device, including applied voltages (Vgs and Vds), physical dimensions like length and width, and material properties like oxide thickness and dielectric constant. Each of these factors plays a vital role in the behavior and performance of electronic components.

Think of a highway (the device) where cars (current) are driving. The number of lanes (width), the distance between exits (length), road conditions (dielectric constant), and even speed limits (mobility of electrons) all contribute to how fast and how many cars can travel to their destination.

As a circuit designer what will be looking for if the device it is already fabricated. So, W’s and L’s they are already defined then we will be looking for the dependency of I as function of Vgs and Vds. And, as a device engineer you may try to change this t you may try to change probably in the surface so that the mobility it will be better and so and so.

Here we differentiate between circuit designers and device engineers. The circuit designer focuses on understanding how current varies with the applied voltages once the device's geometry is fixed, while the device engineer might adjust specific parameters to improve performance. This distinction is important since tasks and goals vary depending on the aspect of the circuitry being worked on.

Consider a chef (circuit designer) who needs to adjust a recipe based on the ingredients already available. The chef does not change the ingredients but works with them to create a dish (design performance) versus a farmer (device engineer) who actively changes soil quality or crop types (device parameters) to improve future harvests (device output).

If you are a VLSI circuit designer where the device yet to be implemented. However, technology is fixed; that means, these parameters are fixed. So, you may say that whenever we say technology is fixed device parameters are fixed, but then you also have the flexibility to change the W's and L's of the devices.

In this final chunk, we focus on VLSI (Very Large Scale Integration) circuit designers who work with fixed technology parameters. They have the ability to alter the width and length of their devices to optimize performance while being limited in other aspects. This innovative flexibility allows them to tailor designs to achieve desired specifications in modern circuits.

Think of a landscape designer (VLSI circuit designer) who cannot change the type of soil (fixed technology) but can layout plants in different shapes and arrangements (adjust W's and L's) to create an aesthetically pleasing garden that flourishes.

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