Amplifiers with Feedback: AC-Analysis and Hybrid-Pie Transistor Model

In summary, the conversation discusses the use of hybrid-pi transistor model to determine amplifier parameters such as input impedance (Rin), output impedance (Ro), mid-band gain (A), low and high cut-off frequencies (fL and fH), and bandwidth (BW) for series-series and shunt-shunt amplifiers with feedback. The formulas for the amplifiers are also mentioned, including the use of feedback to adjust the input and output impedances. However, the specific values for voltage (V_o), current (I_i), and feedback current (I_f) are not provided.
  • #1
jafferrox
25
0
I have attached two different amplifiers with feedback, one of them is series-series amplifier and the second one is a shunt-shunt amplifier.

AC-Analysis:
Using the Hybrid-Pie transistor model
• Determine the amplifier parameters Rin, Ro , Mid-band gain A
• Determine the low cut-off (3-dB) frequency (Low-frequency Pole fL)
• Determine the High cut-off (3-dB) frequency (High-frequency Pole fH)
• Determine the Band Width (BW) and BW x Gain product.

Homework Statement





Homework Equations


ٍseries-series:
A = I_o / V_i
B = V_f / I_o
A_f = A / (1+BA)
R_if = R_i * (1+BA)
R_of = R_o * (1+BA)

shunt-shunt:
A = V_o / I_i
B = I_f / V_o
A_f = A / (1+BA)
R_if = R_i / (1+BA)
R_of = R_o / (1+BA)


The Attempt at a Solution

 

Attachments

  • shshamplifier.png
    shshamplifier.png
    5.5 KB · Views: 429
  • ssamplifier.png
    ssamplifier.png
    6.3 KB · Views: 441
Last edited:
Physics news on Phys.org
  • #2

The Attempt at a Solution


Where is your attempt?
 
  • #3
i could only draw the ac circuit for the shunt-shunt amplifier with the feedback

i already know the formulas for the shunt-shunt:
A = V_o / I_i
B = I_f / V_o
A_f = A / (1+BA)
R_if = R_i / (1+BA)
R_of = R_o / (1+BA)

But i don't know how to find V_o, I_i, I_f?
 

Attachments

  • wo.jpg
    wo.jpg
    31.4 KB · Views: 411

1. What is feedback in amplifiers?

Feedback in amplifiers refers to the process of taking a portion of the output signal and feeding it back to the input of the amplifier. This allows the amplifier to adjust its output based on the input signal, resulting in improved performance and stability.

2. What are the types of feedback in amplifiers?

There are two main types of feedback in amplifiers: positive feedback and negative feedback. Positive feedback increases the gain of the amplifier, while negative feedback reduces the gain and improves stability.

3. How does feedback affect the performance of an amplifier?

Feedback can greatly affect the performance of an amplifier. When properly implemented, negative feedback can improve linearity, reduce distortion, and increase bandwidth. However, too much feedback can lead to instability and oscillations.

4. What are the advantages of using feedback in amplifiers?

The use of feedback in amplifiers has several advantages, including increased linearity, reduced distortion, and improved stability. It also allows for greater flexibility in the design of amplifiers and can help compensate for variations in components.

5. What are the potential drawbacks of using feedback in amplifiers?

While feedback can improve the performance of amplifiers, it can also have some drawbacks. These include increased noise, reduced gain, and the potential for instability if not properly implemented. Additionally, using feedback can make the amplifier more complex and increase the cost of production.

Similar threads

Engineering Unable to model Transresistance amplifier with feedback correctly
    • Engineering and Comp Sci Homework Help
Replies
1
Views
264

Hot Threads

Recent Insights

Back
Top