Question

Question 1 In the diagram of Superheterodne AM receiver shown below explain the function of each block. (a) 15 marks Antenna Speaker Audio and power amplifiers RF IF Mixer Detector Mi amplifier amplifier AGC --_Local Gang tuned oscillator (b) For a 4-bit DAC, calculate the output voltage for an input code word 1010 if a [10 marks] logic 1 is 10V and a logic 0 is 0V, and R = RFI kΩ Total: 25 marks] Question 2 (a) Explain the working of a Basic Series Voltage Regulator. Explain the terms Line regulation and Load regulation. [15 marks] (b) Find the value of Rf for the following circuit to operate as an oscillator. What [10 marks] is the frequency of oscillation? Rf CT C2 C3 ont 0.001 μF | 0.00 | μF | 0.00 | μF Total: 25 marks] Question 3 (a) Explain the following the difference between the following using frequency plots. (i) Butterworth Response Curve (ii) Chebyshev Response Curve (ii) Bessel Response Curve [5 marks] [5 marks] [5 marks] (b) What is the center frequency of a filter with a Q of 12 and a bandwidth of 2.0KHz? [10 marks] [Total: 25 marks] Question 4 (a) Draw and explain the operation of the following op-amp circuits with any relevant equations 7 marks] [4 marks] [4 marks] (i) Basic Differential Amplifier (ii) Op-Amp Integrator (ii) Op-Amp Differentiator (b) Determine the weight of each input voltage for the following scaling adder shown below and find the output voltage. [10 marks] INi +3 V 50 k2 10 k2 IN2 2 V 100 kí2 OUT 10 kΩ [Total: 25 marks] Question 5 (a) Explain the operation of the following with relevant diagrams and equations: 14 marks] 14 marks] 7 marks] (i) Class C Power Amplifier (ii) Class AB Power Amplifier (ii) Class D Power Amplifier and PWM control (b) Using circuit diagrams and equations, explain the small signal model of an emitter follower amplifier. What are the input and output impedences? [10 marks]

Answer 1

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