Tutorial Chapter 1 - Ans

(You must compute the input and output power levels first). 69.7 dB 14. An amplifier has a power gain of 28 dB. The input power is 36 mW. What is the output power? 22.71 W 15. A circuit consists of two amplifiers with gains of 6.8 and 14.3 dB and two filters with attenuations of -16.4 and -2.9 dB. If the output voltage is 800 mV, what is the input voltage? 650.4 mV 16. Given a three-stage system comprised of two amplifiers and one filter with an input power of 0.01 mW and absolute power gains of 200, 0.1 and 1000, determine (a) the gain of each of the three stages in decibel 23dB, -10 dB, 30dB (b) the overall gain in decibel. 43 dB 17. Determine the overall noise factor and noise figure for three cascaded amplifiers with the following parameters:  A1 = 3 dB, A2 = 13 dB, A3 = 10 dB, NF1 = 10 dB, NF2 = 6 dB, NF3 = 10 dB F = 11.725, NF = 10.7 dB 18. Determine the noise figure for an amplifier with an input signal-to-noise ratio of 100 and an output signal-to-noise ratio of 50. 3 dB 19. A transistor amplifier has a measured S/N power of 50 at its input and 10 at its output. (a) calculate the Noise Figure, F (b) calculate the Noise Factor, NF 5, 6.99 dB 20. An amplifier with noise figure, F equal to 6 dB has Si/Ni of 25 dB. Calculate the So/No in (a) dB and (b) as a ratio. 79.454, 19 dB 21. Calculate the input signal-to noise ratio for an amplifier with an output signal-to-noise ratio of 16 dB and a noise figure of 5.4 dB. 21.4 dB 22. A piece of communication equipment has two stages of amplification with gains of 40 and 60 and two loss stages with attenuation factors of 0.03 and 0.075. The output voltage is 2.2 V. What are the overall gain (or attenuation) and the input voltage? 5.4, 0.4074 V 23. A communication system has five stages, with gains and attenuation of 12, -45, 68, -31, and 9 dB. What is the overall gain? 13 dB 24. A power amplifier has an output of 200 W and an input of 8 W. What is the power gain in decibels? 14 dB

25. Three amplifiers with gains of 15, 22 and 7 are cascaded; the input voltage is 120  V. What are the overall gain and the output voltages of each stages? 44, 1.8 mV, 2.64 mV, 840 V 26. A transmitter system with a bandwidth of 30 MHz using an amplifier with a power gain of 50 dB. The system operates at the temperature of 290 K. If the output noise power generated is 100 nW, determine noise figure, NF of the system. 9.2 dB

SUBJECTIVE QUESTIONS

1. 2. 3. 4.

Define modulation and demodulation. What is meant by the term man-made noise? Give several examples. What is the most significant form of internal noise? Explain the main differences between the correlated noise and uncorrelated noise. List and describe two most significant forms for each noise. 5. Define the signal-to-noise power ratio. What do you mean by noise factor and noise figure.

25. Three amplifiers with gains of 15, 22 and 7 are cascaded; the input voltage is 120  V. What are the overall gain and the output voltages of each stages? 44, 1.8 mV, 2.64 mV, 840 V 26. A transmitter system with a bandwidth of 30 MHz using an amplifier with a power gain of 50 dB. The system operates at the temperature of 290 K. If the output noise power generated is 100 nW, determine noise figure, NF of the system. 9.2 dB

SUBJECTIVE QUESTIONS

1. 2. 3. 4.

Define modulation and demodulation. What is meant by the term man-made noise? Give several examples. What is the most significant form of internal noise? Explain the main differences between the correlated noise and uncorrelated noise. List and describe two most significant forms for each noise. 5. Define the signal-to-noise power ratio. What do you mean by noise factor and noise figure.