# Week5Lab7CCAmplifier-OL.docx

EET120

Semiconductor Devices

Experiment 7: The Common-Collector Amplifier

Objectives:

After completing this experiment, you should be able to,

1. Calculate and measure the DC & AC parameters of the Common-Collector (CC) amplifier.

2. Observe the effect of the by-pass capacitor on amplifier voltage gain.

Components needed:

1. Resistors: (1) 33 kΩ, 10kΩ, 100 Ω, (2) 1kΩ

2. Capacitors: 1 µF, 10 µF

3. Transistor: (1) PNP – 2N3906

4. Multisim

Procedure:

1. Build the following circuit in multisim.

VCC12V

Q1

2N3906

R1

33

R2

10

RC

100Ω

RE

1

# Figure 1: DC Equivalent circuit of CC amplifier

2. Calculate the DC parameters listed in Table 2 for the circuit shown in Figure 1.

 DC Parameters Calculated Value Measured value VB 2.79V 3.12V VE 3.49V 3.88V IE 8.51mA 8.12mA VC 851mV 807mV VCE -2.64V -3.076V

# Table 2: Calculated and measured DC parameters

3. Measure and record the values in Table 2 using the DMM.

4. Modify the circuit as shown in Figure 2.

Q1

2N3906

VCC

V

12

Pin 49

R1

33

R2

10

RC

100Ω

C1

µF

1

VS

0.5

Vppk

1

kHz

0

°

C3

10

µF

RL1

1

RE

1

Figure 2: The Common – Collector Amplifier

 Input voltage VIN Output voltage VOUT Voltage gain AV 500mVPP 494mV 0.988 1VPP 970mV 0.97 2VPP 1.934V 0.967 3VPP 2.9V 0.97

# Table 3: Calculated and measured AC parameters

10. Set the AC Source voltage to 500mVPP, 1 kHz sinewave.

11. Connect the first channel of the Oscilloscope across the AC source.

12. Connect the second channel of the Oscilloscope across the 1 kΩ load resistor.

13. You should be able to observe the signals as shown in Figure 3. Note: your scope screen may look different.    # Figure 3: Input and Output signals of the CE Amplifier

14. By observing the input and output signals of the amplifier, the phase difference between them is approximately _____0____ degrees.

15. Record the output voltage Table 3.

16. Calculate the voltage gain (Av) using the measured input and output voltages using the formula below. Record the result in Table 3 under Voltage gain Av.

Voltage gain

17. Repeat step 15 and 16 by changing the input voltage as shown in Table 3 and record the results.

18. Summarize your observations on voltage gain below.

# image4.png 