Lab 8 TF EIM

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Lab 8 The Diode Objective: Measure the current-voltage curve of a silicon diode.

Reverse current

1.) Construct the circuit below using a DC power supply, a diode.

Lab8 ReverseCurrentDiode.png

2.) attach an Oscilloscope set to 1M[math]\Omega[/math] input impedence so the probe is located at point B. The oscilloscope's internal resistance will serve as a Resistor (R) to measure the voltage across the diode and calculate the current.

3.) Measure the diode reverse current [math]I_r \lt 1 \mu A[/math] as a function of the DC supply voltage. (30 pnts)

Bias Volts V_{scope} (1 M\Omega)(mV) Current (V/R) Power

4.) Fill in the blank. The reverse biased diode act as a constant _______________ source. (5 pnts)

Forward Current

  1. now swap the diode direction and repeat the measurement in the previous section.

Lab8 ForwardCurrentDiode.png


  1. make the same measurements in parts 1 and 2 above for a germanium diode.
  2. Plot the diode current (on the ordinate) versus the diode voltage (on the abscissa)for both diodes on the same graph. (50 pnts)


  1. The reverse biased diode acts like a constant ____________. (10 pnts)
  2. The forward biased diode has a very __________ resistance. A reverse biased diode has a very ____________ resistance.(10 pnts)
  3. The approximate DC forward resistance for diode #___________ is _________ when the forward current is _______________.(10 pnts)
  4. The approximate DC reverse resistance for diode #___________ is _________ when the forward current is _______________.(10 pnts)
  5. The silicon diode #___________ has an approximate turn on voltage of ___________.(10 pnts)