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JANUARY 2018 CONFIDENTIAL

INSTRUCTION: Answer ALL questions.

Please use the answer booklet provided

Question 1

1. Figure 1 shows the BJT transistor power amplifier. Calculate:

1. The power dissipation (8 marks)

2. The efficiency (8 marks)

Figure 1

1. Describe the characteristic, advantages, disadvantages and applications of each of the classes (A, AB, B, and C) of power amplifiers (9 marks)

Question 2

(a) Given a voltage divider JFET amplifier that has VDD = 20 V, VP = -4 V, VGSQ = -0.5 V, R1 = 82 MΩ, R2 = 11 MΩ, RD = 2 kΩ, RS = 610 Ω, RL = 10 MΩ and IDSS = 8 mA. Analyze the DC and AC performances of the given JFET amplifier. (25 marks)

Question 3

1. Construct the summing amplifier based on the Op-Amp circuit that consist of three input signals of V1, V2, and V3 and also one output Vout. (3 marks)

1. Prove the following equation for the summing amplifier: (8 marks)

1. Describe four different types of active filter and sketch their expected frequency responses

(8 marks)

1. Describe the construction, operation and characteristic of Shockley diode. (6 marks)

Question 4

1. For the given Figure 2

1. Determine gm0 and gm (4 marks)

2. Determine Av and Avs in the mid-frequency range (4 marks)

3. Determine fHi and fHo (8 marks)

4. Determine the cut-off frequencies (2 marks)

5. Sketch the asymptotes of the Bode Plot defined by the cut-off frequencies of part (iv)

(3 marks)

1. Determine the high frequency response for the amplifier using the results of part (v) (4 marks)

Figure 2

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