54.3.1. Design Guidelines

So, welcome back after the short break. ... the achievable performance of the circuit, then only a week this exercise is meaningful.

This chunk introduces the importance of ensuring that our design specifications align with the achievable performance of the circuit components. If the specifications, such as voltage gain and output swing, are not realistic given the components used, the design process will not yield useful results. For example, expecting a voltage swing greater than the power supply voltage is impractical.

Imagine trying to fill a large swimming pool with a garden hose; if the hose can't deliver enough water, no matter how hard you try, the pool will never fill. Similarly, in circuit design, if your components can't deliver the desired output, the design won't work.

First of all we are assuming that the supply voltage is given to us ... it should be such that the V_GD should be at least 3 V.

In this chunk, we learn about calculating DC voltages required for proper operation of the circuit. The output swing must be defined, and the DC voltage must ensure that the MOSFET operates in saturation. Based on the desired output swing of ± 4 V, we derive that a certain DC voltage must be maintained at different nodes to prevent the transistor from entering the triode region.

Think of it like maintaining the water level in a tank; if you want a specific amount of water to flow out, you need to keep the inlet above a certain height. In circuits, the 'height' of the voltage must be maintained to ensure proper operation.

And now so, we obtained this ratio relative value ... typically to reduce this DC current flow here we may consider this is in the order of 10 kΩ.

This section discusses determining the values of resistors to achieve specific voltage drops needed for optimal circuit performance. It emphasizes the importance of maintaining a ratio between resistors, which directly influences the desired voltage at the gate of a transistor. Choosing appropriate resistor values is crucial for achieving overall circuit characteristics like gain and input impedance.

Choosing resistor values in a circuit is like selecting the right size pipes for plumbing; the wrong size can create bottlenecks, impacting the system's efficiency. Just as one needs to calculate the right size for water flow, one needs to calculate resistor values to ensure optimal electrical flow.

So, we may have to replace this one ... and that is mainly because the R_it is comparable with a R_T2.

This chunk highlights the relationship between input impedance, current gain, and the selected resistors. It explains how to achieve a specified input impedance by calculating the required current and subsequently determining the resistor values based on Ohm's Law. A higher input impedance ensures minimal loading on the source stage.

It's like fitting a wide entrance to a concert hall to allow more people inside easily. In electrical terms, a higher input impedance allows the circuit to accept signals without distortion or loss.

So, what we obtain here it is let me summarize ... voltage gain of this amplifier it is expected to be high.

In this concluding section, we summarize the key objectives and details achieved through design calculations. The result emphasizes that while targeting specific voltage gains in amplification circuits, one must also balance between current requirements and resistance values. The result indicates that real-world components often result in lower-than-expected gains, emphasizing the need for practical considerations in design.

Think of a restaurant aiming to serve a limited number of diners quickly. Simply hiring more staff isn't enough; one must also consider kitchen space, ingredient availability, and even customer flow. Similarly, achieving high voltage gain requires careful planning of all circuit components, not just adjusting one element.

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