22.1.2. Concepts to be Covered

What are the concepts we are going to cover today? It is, basically as I said that the model of voltage amplifier, then model of current amplifier, model of trans-conductance amplifier and trans-impedance amplifier.

In this section, we introduce the different types of amplifier models that will be discussed. First, we focus on the voltage amplifier, which enhances voltage levels. Next, we delve into the current amplifier that enhances current levels. Following that, we explore the trans-conductance amplifier which relates current at its output to voltage at its input, and the trans-impedance amplifier, which converts input current to output voltage. Together, these represent the essential amplifier configurations.

Think of these amplifier models as different tools in a workshop. Just like a hammer is used to drive in nails (voltage amplifier), a wrench is used to tighten bolts (current amplifier), a plier is used to hold wires (trans-conductance amplifier), and a screwdriver is used to turn screws (trans-impedance amplifier). Each tool serves a specific purpose, helping you achieve your project goals efficiently.

So, primarily we will be discussing more detail of these two topics and whatever the idea we will be gaining from that, we will be extending to the other two types of amplifiers quickly.

This chunk emphasizes that the lecture will focus first on voltage amplifiers and, after establishing a comprehensive understanding, will streamline into discussing the current amplifier and the trans-conductance and trans-impedance amplifiers. This method allows for depth in understanding, which can then be applied to understand the other amplifier types.

Imagine learning to bake a cake by first mastering the batter. Once you create a perfect batter (understanding the voltage amplifier), you can easily adapt that knowledge to make other desserts like muffins and pancakes (core concepts applicable to other amplifier types).

Say for example, the first one it is; it consist of BJT, second one it is having a MOS transistor. And for each of the cases what we have here it is, the DC voltage source and then of course the ground and along with the biasing element resistor.

In this section, two specific types of voltage amplifiers are mentioned: one using a Bipolar Junction Transistor (BJT) and the other a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET). Both configurations involve a DC voltage source and additional components like resistors that help bias the transistors into their active regions, which is essential for their amplification properties.

Consider these voltage amplifiers like different vehicles: a BJT might be like a compact car, great for city driving (efficient and effective for small tasks), while a MOSFET might be like a sports utility vehicle (SUV), built for a powerful performance over diverse terrains (more robust and suitable for varying conditions). Both transport you, but they do so in different manners.

So, whenever we are going for say model or linearization basically what you do; as I said that the transistor we are keeping in the appropriate region of operation, and then after that we try to find what is the relationship between the applied voltage here to whatever the corresponding output we are getting.

This chunk explains the concept of linearization in modeling, which involves ensuring that the transistor operates in the correct region (active region) for accurate amplification. The main focus here is to understand how the input voltage applied correlates to the output voltage produced, which is critical in designing amplifiers.

Picture tuning an instrument, like a guitar. You have to adjust the tension of each string (keeping the transistor in the correct region) until it produces the right note (accurate output). If the strings are too tight or too loose, the notes won’t sound right, just like an amplifier can fail to deliver clean output if the transistors aren't correctly biased.

So, whenever you are talking about modelling of voltage amplifier what does it mean is; we like to change the circuit, whole circuit by an equivalent circuit or you can say equivalent linear circuit, which primarily correlates the small signal output with respect to whatever the small signal input we are giving.

Modeling a voltage amplifier often involves simplifying the complex circuits into equivalent linear circuits. This means substituting the entire circuit with a simpler model that captures the relationship between small input signals and the resulting small output signals, making analysis and understanding easier.

Think of simplifying a long recipe into key steps. Instead of detailing every single action needed (the complex circuit), a simplification could distill it down to just 'mix ingredients, bake, and serve' (the equivalent linear circuit). This makes it easier to follow and understand how the final dish (output signal) is achieved from the raw components (input signal).

So, we may say that to again to summarize what we said is; that we like to get the input to output signal relationship primarily. So, this is the say, you may say that input signal...

This part summarizes the key parameters that will be important in the study of amplifiers: the voltage gain, input resistance, and output resistance. Understanding these parameters allows engineers to analyze and anticipate how the amplifier will behave under different loads and conditions.

Consider this as setting up a team for a project. The 'voltage gain' is the skill level of the person leading (how effectively they move the project forward); the 'input resistance' is the support system (like having strong team members) that influences how well tasks get done, and the 'output resistance' might illustrate how external factors (like deadlines) impact the team's performance.

--