Question

Notify Me Bookmark

A feedback amplifier circuit is shown in Figure Q4. Figure Q4: Feedback Amplifier (a) What type of feedback topology is used in this amplifier? (b) Redraw the amplifier circuit, replacing the op-amp with the equivalent circuit for this feedback topology. (c) Estimate the current, Io, the feedback gain, Aif in dB, and the amplitude of the AC voltage, vo, when RF = 150 kΩ, R1 = 4.7 kΩ, RL = 820 Ω, and Ii = 40 μAp−p at 1 kHz.

A feedback amplifier circuit is shown in Figure Q4. Figure Q4: Feedback Amplifier (a) What type of feedback topology is used in this amplifier? (b) Redraw the amplifier circuit, replacing the op-amp with the equivalent circuit for this feedback topology. (c) Estimate the current, Io, the feedback gain, Aif in dB, and the amplitude of the AC voltage, vo, when RF = 150 kΩ, R1 = 4.7 kΩ, RL = 820 Ω, and Ii = 40 μAp−p at 1 kHz.

Image text
A feedback amplifier circuit is shown in Figure Q4. Figure Q4: Feedback Amplifier (a) What type of feedback topology is used in this amplifier? (b) Redraw the amplifier circuit, replacing the op-amp with the equivalent circuit for this feedback topology. (c) Estimate the current, I o , the feedback gain, A i f in d B , and the amplitude of the AC voltage, v o , when R F = 150 k Ω , R 1 = 4.7 k Ω , R L = 820 Ω , and I i = 40 μ A p − p at 1 k H z .

Detailed Answer

0 0

Please enter your email here. You will get email when this question is answered by our tutor.

Doubtrix Logo

Problem is not yet solved!

Click on Notify me to get email when question is answered.

Join Doubtrix with 7-days free trial

  • Icon Correct & Verified Answers
  • Icon No AI-Generated Answers
  • Icon Video Solution for Difficult Questions
  • Icon Work With Experts to Reach at Correct Answers
Notify me Login Sign Up

Similar/Related Questions

Assume that the MOSFET has the following parameters: Vt = 1 V, K = 0.4 mA/V2 VA = 40 V. It is connected as an amplifier as shown in Figure Q4 and vs is an AC input voltage and vo is the AC output voltage. The DC drain voltage VD is set to be 0 V. Further assume that all the capacitors in the circuit are very large. Figure Q7. (a) Which type of amplifier configuration does the above circuit (3 marks) belong to? What are the electrical properties of this type of amplifier configuration? (b) Show that the MOS transistor operates in the saturation mode. (3 marks) State one electrical characteristic of a saturated MOS transistor. (c) Determine the drain current ID. (10 marks) (d) Design the load resistance RL such that the AC voltage gain vo/vs of (10 marks) the MOSFET amplifier equals -10 . (e) Suppose the amplitude of AC input vs is 0.2 V and the AC voltage (4 marks) gain of the amplifier equals -10. Do we have a distorted AC output waveform?

Solution
0 0

Q2 - For the amplifier circuit in Figure Q2, VDD = 6 V, IB = 1 mA, RG1 = RG2 = 2 MΩ, RL = 10 kΩ, and CA = C2 = 0.1 μF. The transistor is characterized by the following parameters. Vs = 0.5 V, kn = 2 mA/V2, and VA = 20 V Figure Q2. (a) Find Vov and VGs for the transistor. Ignore channel length modulation for this part. (b) What is the midband gain of the amplifier? (c) What is the input impedance (Rm) of the amplifier? (d) What is the output impedance (Ro) of the amplifier? (e) Find the lower −3 dB cutoff frequency (fL). (f) Construct the small signal equivalent circuit in Ltspice and run an AC simulation. Mark the lower -3 dB(f1) frequency. Compare it to your hand calculation.

Solution
0 0

Consider the amplifier circuit in Fig. 4 which amplifies input Vin to output Vout. The circuit accomplishes this by using a bipolar junction transistor or BJT. The BJT is a three-terminal circuit element with nodes B, C, and E. In some situations, the BJT can be modeled with an equivalent linear circuit containing a voltage-dependent current source as shown in Fig. 5. Figure 4: Amplifier circuit with BJT Figure 5: Equivalent circuit model for BJT We want to find the Thevenin and Norton equivalent of the amplifier circuit across the terminals Vout (i. e. , between nodes C and E ). Note: You can use the parallel operator (||) in your final answers. (a) Redraw the original amplifier circuit in Fig. 4 but with the BJT equivalent circuit model in Fig. 5 substituted. (b) Use the open circuit test to find the Thevenin voltage, Vth , between nodes C and E. Recall the open circuit test finds Vout = Voc when an open circuit is connected across the terminals, then Vth = Voc. (c) Use the short circuit test to find the Norton current, Ino, between nodes C and E. Recall the short circuit test finds Iout = Isc when a short circuit is connected between the terminals, then Ino = Isc. (d) Find the Thevenin/Norton resistance Rth = Rno using Rth = Vth Ino. (e) We can also find Rth by turning off all of the independent sources (but not the dependent sources) and deriving the equivalent resistance seen from the terminals. Derive Rth with this method. Does it match your answer from part (c)? Hint: To simplify the dependent source, focus on first finding VBE.
Solution
0 0