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Which types of applications are field-effect transistors preferred over bipolar

ID: 2083382 • Letter: W

Question

Which types of applications are field-effect transistors preferred over bipolar junction transistors? Why?

Explain why junction field-effect transistors are considered voltage-controlled devices.

EQUIPMENT

1 power supply: 15V

1 transistor: 2N4860

3 resistors: 1k, 4.7k, 2M

<List meters used>

PROCEDURE

Using Multisim construct the circuits shown below:

Measure the following and record the values in the “results” section: VG, ID, VS, VD, VDS,

RESULTS

Calculate VGS from the measured values.

Which type of biasing is used?

The table below shows readings for three different cases where the circuit above, was malfunctioning. Find the fault, assuming only one device in each case has a problem. List the steps taken to arrive at a solution.

VDS

VD

VS

What is the problem?

1

91.4mV

91.4mV

0V

2

66.5mV

15V

14.9V

3

15

15

0

CONCLUSION

What did you learn?

VDS

VD

VS

What is the problem?

1

91.4mV

91.4mV

0V

2

66.5mV

15V

14.9V

3

15

15

0

2MQ VDD 15V R2 4.7k Q1 2N4860 R3

Explanation / Answer

Applications of FET:

1.Input stage of oscilloscope.

2.Input stage of electronic volt meters.

3.Low noise amplifier.

4.Buffer amplifier.

5.Cascode amplifier.

6.Analog switch.

7.Chopper amplifier.

8.Muliplexer.

Reason: very high input impedance.