ENTC 4350 HOMEWORK SET 3 Chapter 5.

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ENTC 4350 HOMEWORK SET 3 Chapter 5

Chapter 5, Problem 4. Calculate the noise voltage between dc and 1000 Hz due to thermal agitation in a circuit containing only a 75-W resistor.

Chapter 5, Problem 6. What is the shot-noise level over the bandwidth dc to 20 kHz in a conductor in which 100 mA flows?

Chapter 5, Problem 7. Two noise sources are present in a circuit: a voltage source that produces 50 mV (rms), and a current source in which a 120 nA current flows in a 100-W resistance. What is the average noise voltage of this circuit?

Chapter 5, Problem 8. A circuit has a noise figure of 4.7 dB. Calculate the noise factor.

Chapter 5, Problem 10. Three amplifiers in cascade have the following characteristics: Calculate the noise factor for the entire chain. Amplifier Gain Noise Figure (dB) A1 100 2.1 dB A2 10 10.8 dB A3 5 5.4 dB

Chapter 5, Problem 10. Convert the noise figures into noise factors:
Use Friis’s equation:

Chapter 5, Problem 10. Use Friis’s equation:

Chapter 5, Problem 11. Reverse the order of the amplifiers in problem 10 (i.e. exchange A1 and A3), and recalculate the noise factor. Compare the results. Amplifier Gain Noise Figure (dB) A1 5 5.4 dB A2 10 10.8 dB A3 100 2.1 dB

Chapter 5, Problem 11. Use Friis’s equation:

Chapter 5, Problem 12. An op-amp has an open-loop gain of 1,000,000. Calculate the closed loop gain when b = 0.10.

Chapter 5, Problem 13. An EEG signal processes a 10 mV signal in the presence of 125 mV of random noise. Calculate the processing gain and processed SNR if signal averaging of 256 repetitions of the waveform is performed.

Chapter 5, Problem 13.