58.1.4. Recapitulation of Previous Numerical Example

So, here again the same summary here the concepts we already have covered particularly the theoretical aspects of mixing different configurations are covered. And, we are going to discuss about numerical examples of particularly for CE followed by CC common collector stage to enhance the bandwidth of the amplifier and. So, similarly for MOS counterpart common source followed by common drain, it gives the enhancement of the bandwidth.

This chunk summarizes the focus of the section, which is the application of theoretical knowledge of different transistor configurations, particularly the Common Emitter (CE) followed by Common Collector (CC) to enhance the amplifier's bandwidth. Also mentioned is the importance of MOS configurations that parallel these enhancements.

Think of an amplifier like a water pipe. The different configurations (like CE and CC) can be thought of as different widths or arrangements of the pipe that affect how much water can flow through (or the signal bandwidth in this case). By optimizing these configurations, we can improve the flow rate significantly.

So, this slide is a recapitulation of one of our previous numerical examples where we have discussed about CE amplifier having fixed bias arrangement and different parameters are given here including the supply voltage of 12 V, then device parameters including β of the transistor, early voltage, then V and BE(on) then also we do have the bias circuits resistances are given here R then collector resistor B and so and so.

This chunk lists the essential parameters set for the Common Emitter amplifier. Parameters such as supply voltage (12V), transistor properties (like gain represented by β, Early voltage, and V_BE(on)), along with the resistances in the bias circuits and collector resistors are outlined. Each of these components plays a crucial role in determining the operating point and performance of the amplifier.

Imagine setting up a model train track. You have to make sure the power source (supply voltage), train specifications (transistor parameters), and track supports (resistances) are correctly chosen to ensure the train runs smoothly. Any mismatch can lead to poor performance.

Let us try to see the operating point of the transistor...using this information and the β information we are getting the collector current which is equal to 2 mA.

In this chunk, the calculation of the transistor's operating point is explained. The operating point is the DC bias point that ensures the transistor operates correctly in the active region. By using Kirchhoff's Current Law (KCL) and identified parameters, the base and collector currents are computed (20 µA and 2 mA respectively). This step is crucial for determining how the amplifier will respond to signals.

Consider a light dimmer. The position of the dimmer switch defines how much power reaches the light bulb (operating point). If it's set too low (below the active region), the bulb doesn’t light well just like a transistor not operating correctly outside its bias range.

Now, we obtained the small signal parameters value namely g_m...and r_o resulting in voltage gain calculations.

This chunk discusses how to derive small signal parameters such as transconductance (g_m) and output resistance (r_o) based on the collector current calculated earlier. These parameters enable the computation of voltage gain—essential for quantifying how effectively the amplifier amplifies input signals.

Imagine tuning a musical instrument. The finer the adjustments you make (calculating small signal parameters), the better the sound quality (amplifier gain). Each small tweak can have a significant impact on overall performance.

Now, the exercise we are going to do it is that we are going to put in this case instead of putting the capacitor here we can probably directly put a CC stage here...

This chunk introduces the approach of utilizing a CC stage to enhance the amplifier's bandwidth rather than adding coupling capacitors. It discusses how this setup allows for better bandwidth performance and calculates new cutoff frequencies, signifying improved amplifier efficiency.

Think about the difference between a narrow road versus a wide highway. By adding a CC stage, you essentially broaden the road, allowing for more cars (signals) to pass through at higher speeds (better bandwidth).

So, the value of this upper cutoff frequency can be obtained by considering that 3.1 k multiplied by 10 sorry 100 pF which is 10‒10.

In this section, the upper cutoff frequency is discussed alongside its relation to the output resistance and capacitance. By including these parameters, calculations reveal essential information about the frequency response and limits of the amplifier’s performance.

This is like determining the frequency response of a speakers—where sound gets muffled above certain pitches. By calculating the cutoff frequency, you are identifying the point beyond which the audio signal cannot effectively be transmitted.

So in summary what we have circuit performance why should you have the circuit gain is 238 and then the upper cutoff frequencies 513 kHz.

This final chunk presents a summary of the results achieved from the previous calculations. The overall gain and bandwidth results showcase the improvements and effectiveness of including the CC stage in the configuration, emphasizing the practical application of the theoretical concepts discussed throughout this section.

Think of the amplifier as a competitive athlete. The gain (strength) and cut-off frequency (speed) are akin to their performance statistics. By improving training (adding CC stage), the athlete becomes even stronger and swifter, ready to outperform competitors.

--