8/13/2019 Lab 1 Silicon Diode S21314

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EEEB 141 Electronics Design Lab -Lab 1 2

BACKGROUND

Diode is a device formed from a junction of p-type and n-type semiconductor materials. The

lead connected to the p-type material is called anode while the lead connected to the n-

type material is called cathode. Normally, the cathode of a diode is marked by a solid line

on the diode.

One important application of diode is rectification. When it is forward biased (higher

potential connected to the anode), the diode will allow current to pass. When it reversed

biased (higher potential connected to the cathode), the current is almost zero or blocked.

The diode can be thought of a switch that closes (on) when the diode is forward biased, and

opens (off) when diode is reversed biased.

Another important characteristic of a diode is the reverse bias breakdown. Applied reverse

bias voltage cannot increase without limit. At some point, breakdown occurs and the

reverse-bias direction increases rapidly. Breakdown may damage to a normal diode.

However, diodes called Zener diodes can be designed and fabricated to provide a specific

breakdown point.

CathodeAnode

Forward Bias

Region

Reverse Bias

RegionReverse Bias

Breakdown Region

I

V

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IN-LAB ACTIVITIES

1. Measure and record the resistance of the resistors. Construct the forward-biasedcircuit shown in Figure 1-1. Set the power supply for zero volts.

Figure 1-1

2. Monitor the forward voltage drop, VD,FOR, across the diode, D1. Slowly increase VSto establish 0.35V across the diode. Measure the voltage across the resistor, VR1,

and compute ID FOR. Record and tabulate the data based on VD,FOR in Table 1-1.

3. Connect the reverse-biased circuit shown in Figure 1-2. Record and tabulate thedata in Table 1-2.

Figure 1-2

4. Plot graphs of current, I against the output voltage, Vofor the forwardand reversebiased diode circuits graph papers.

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RESULTS

Resistor Resistances

R330 :

R1M : M

Diode Resistances

Forward bias: M

Reverse bias: M

VD,FOR(V)

VS (V) VR1(V)1

R1

D

R

VI

FOR(A)

Nominal Measured

0.35

0.40

0.45

0.50

0.55

0.60

0.65

0.70

0.75

Table 1-1

VS (V)

VR1(V) VD,REV(V)1

R1

D

R

VI (A)

Nominal Measured

5

10

15

20

25

Table 1-2

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POST LAB DISCUSSIONS

Silicon Diode Characteristic

1. Describe your observation/understanding based on the plotted forward biaseddiode curve graph.

2. Discuss the difference from the experimental I-V plot, compared to the ideal diodeI-V characteristic drawn in the pre-lab question.

CONCLUSIONS