Solution Tutorial

ENT 162 Analog Electronics –Power Amplifier

1.Figure 1 shows a CE power amplifier in which the collector resistor serves also as the load resistor. Assume βDC = βac = 100.

(a) Determine the dc Q-point (lCQ and VCEQ).

(b) Determine the voltage gain and the power gain

2. For the circuit in Figure 1, determine the following: (a) the power dissipated in the transistor with no load

(b) the total power from the power supply with no load

(c) the signal power in the load with a 500 mV input

3. Assume a CC amplifier has an input resistance of 2.2 kΩ and drives an output load of 50 Ω. What is the power gain?

4. Determine the Q-point for each amplifier in Figure 2.

Figure 2

5. What is the maximum peak value of collector current that can be realized in each circuit of Figure 2? What is the maximum peak value of output voltage in each circuit? (a)

(b)

6. Find the power gain for each circuit in Figure 2. Neglect re’.

7. Find the maximum output signal power to the load and efficiency for the amplifier in Figure 3 with 500 Ω load resistor.

Figure 3

Maximum output signal power to the load

Efficiency for the amplifier

8. Refer to the class AB amplifier in Figure 4. (a) Determine the dc parameters VB(Ql), VB (Q2), VE, ICQ, VCEQ(Ql), VCEQ(Q2).

(b) For the 5 V rms input, determine the power delivered to the load resistor.

Figure 49. Draw the load line for the npn transistor in Figure 4. Label the saturation current, IC(sat) and

show the Q-point.

These points define the ac load line as shown in Figure. The Q-point is at a collector current of 8.3mA and the dc load line rises vertically through this point.