68.1.14. Conclusion and Next Steps

So, in summary what we can say that the cutoff frequency it is getting reduced gain got increased and output resistance also got increased of course, the input capacitance also got increased.

In this chunk, we summarize the performance changes resulting from the use of an active load in the common emitter amplifier. We observe that the cutoff frequency decreases, the voltage gain increases, the output resistance rises, and the input capacitance also increases. Each of these parameters reflects how active loads can enhance an amplifier's performance, especially in terms of gain, but may compromise bandwidth due to increased capacitance.

Consider a car's engine as an analogy. If you replace a standard engine with a high-performance engine (like using an active load), you can drive faster (higher gain); however, the engine might be more sensitive and react differently at high speeds (leading to reduced bandwidth in terms of how quickly it can respond to changes in signal).

Now if I compare this performance matrices with the performance matrices of CE amplifier having passive load and here we do have the corresponding circuit...

In this section, we directly compare the performance metrics of the CE amplifier with an active load to that of a similar amplifier employing a passive load. The analysis reveals that while the gain is significantly improved with the active load (approximately ten times higher), the bandwidth decreases to nearly one-tenth the previous value. This reflects a trade-off in amplifier design, where increasing gain often leads to bandwidth limitations.

Imagine using a megaphone (active load) to amplify your voice at a concert. You’ll be much louder (higher gain), but the range of your voice clarity might suffer if the megaphone distorts higher frequencies (reduced bandwidth), compared to just shouting without it (passive load).

So, if I multiply this gain and then bandwidth that remains same and hence the gain bandwidth product it remains same.

This chunk discusses the concept of the gain-bandwidth product (GBP), indicating that despite changes in gain and bandwidth with different amplifier configurations, the product of these two quantities remains constant. This principle is critical in electronics as it helps designers understand limits on performance when optimizing gain.

Think of the gain-bandwidth product like a fixed recipe that requires a specific amount of ingredients (gain and bandwidth). If you increase the amount of one ingredient to make a richer cake (higher gain), you’ll have less room for others (lower bandwidth), but the total amount of cake (gain-bandwidth product) you can produce doesn't change.

In my calculation what I have done is that I simply multiplied this gain and this bandwidth and it is coming close to 122 MHz for both the cases.

Here, we conclude by noting that the calculation of the gain-bandwidth product yields around 122 MHz for both active and passive load configurations. This highlights that while the limitations of material properties and circuit design affect amplifier performance, systematic calculations allow us to predict outcomes effectively.

It's similar to measuring the maximum weight an elevator can hold; regardless of whether you use it to carry books (passive load) or people (active load), the maximum capacity (gain-bandwidth product) stays the same, reflecting the static limits of the elevator's design.

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