Please help me with my lab report

1

EECE 315, Pre-Lab Report 02

Name

Date M/T/W/R/F

Collaborators

Pre-Lab

1. In this lab, you will be taking i-v measurements on a forward-biased diode using a series circuit composed by a DC voltage source, a resistor (decade box), and a diode (as shown below).

D1N4148

VR

-

+

Vdiode

-

+

RVsource

2. What order of magnitude of voltages (cut-in voltage or turn-on voltage) do you expect across the diode?

3. Draw an “equivalent circuit” (without a diode, similar to what we have seen in class) for a diode

circuit in DC analysis.

4. Both the voltage source and the resistor can be varied. The maximum DC voltage source is about 20 V. The current through the forward-biased diode should be varied over the four decades between 1 uA and 10 mA. Within each decade, you will take data points at roughly 1, 2 and 5 (so you need to capture data at 1uA, 2uA, 5uA, 10uA, 20uA, 50uA, 100uA, 200uA, and so on). This will provide the data to be more or less evenly spaced along the log scale. Determine what values of DC voltage source and resistance you will use in lab to achieve these values of current, and justify your selection. (Be aware that if you allow the resistance to go much below 2 kΩ, you run the risk that your diode will blow).

Circle one

2

5. In an excel sheet, tabulate your calculation results for VD and ID from equivalent circuit. The

table should look something similar to below.

6. Plot the results in semi-log scale in excel sheet. From MS Office, Excel use, INSERT  LINES  2D Lines with markers (use VD as x-axis, ID as y-asis)

When 2D graph pops up,

Change the y-axis scale to log scale (by double clicking on the y-axis area) Double click on y-axis AXIS OPTIONClick on “Logarithmic Scale”

Linear Scale (default) (Semi)Log Scale

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EECE 315, Final Lab Report 02

Name

Date Mon / Tue

Collaborators

EECE-315 Lab Current in the diode is

)1(  kTn

qV

SD

D

eII

For VD > 0.1 volts, ID  IS e aV where a = q/(nkT).

In this lab, you will measure the i-v characteristics of a 1N4148 diode.

1. Connect the diode, a decade box resistance, and a DC voltage source in series.

D1N4148

VR

-

+

Vdiode

-

+

RVsource

2. Use the resistance you have selected from your Pre-lab. (Be aware that if you allow the resistance to go much below 2 kΩ, you run the risk that your diode will blow). Also try 2 other values. (If your resistor selection is 3kΩ, try 2.5kΩ and 3.5kΩ).

3. Use a digital multimeter (DMM) to measure the voltage across the diode (minimum acceptable precision is three significant digits.)

4. Use another DMM to measure the voltage across the resistance, and then calculate the diode current.

5. Adjust the DC voltage source or the resistance to get the correct current. Tabulate these data points on the excel sheet.

6. Using the same method as PreLab, plot the i-v characteristics. Discuss your results.

Circle one