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EENG341 ELECTRONICS I FALL08 1
DIODE TUTORIALS Ideal Diodes
1. What is the current through the diode and the voltage across the diode for the
following two circuits?
EENG341 ELECTRONICS I FALL08 2
2. What is the output voltage for the following circuit?
3. What is the voltage across the diode?
4. What is the voltage transfer characteristic ( ov vs. iv )?
EENG341 ELECTRONICS I FALL08 3
5. For the following circuit, if sv is a sinusoid with 24-V peak amplitude, find the
fraction of each cycle during which the diode conducts. Find the peak value of the
diode current and the maximum reverse-bias voltage that appears across the
diode.
EENG341 ELECTRONICS I FALL08 4
6. Analyze the following circuits assuming that the voltages are either 0V or 5V.
What logic functions do they perform?
EENG341 ELECTRONICS I FALL08 5
7. Find I and V in the following circuits.
EENG341 ELECTRONICS I FALL08 6
8. Find the values of I and V in the following circuits.
9. Find the values of I and V in the following circuits.
EENG341 ELECTRONICS I FALL08 7
EENG341 ELECTRONICS I FALL08 8
Diode Models
1. Determine the current DI and the diode voltage DV for the following circuit with
5DDV = V and 1R = kΩ . Assume that the diode has a current of 1 mA at a voltage
of .7 V and that its voltage drop changes by .1 V for every decade of change in
current.
2. Repeat Problem 1 using the piecewise linear model assuming
0 0.65V and 20D DV r= = Ω
3. Repeat Problem 1 using the constant voltage drop model.
EENG341 ELECTRONICS I FALL08 9
Diode Circuits & Zener Diodes
1. Design the following circuit to provide an output voltage of 2.4V. Assume the
diodes have a current of 1 mA at a voltage of .7 V and that its voltage drop
changes by .1 V for every decade of change in current
2. Consider the following circuit. What is the percentage change in the regulated
voltage caused by (a) a 10% change in the power-supply voltage and (b)
connection of a 1k load resistance?
EENG341 ELECTRONICS I FALL08 10
3. A 6.8-V Zener diode in the circuit below is specified to have Vz=6.8V at
Iz=5mA, rz=20 ohms, and Izk=0.2mA. The supply voltage is nominally 10V but
can vary by +/- 1V.
a. Find Vo with no load and with V+ at its nominal value.
b. Find the change in Vo resulting from the +/-1V change in V+. Note that
(Vo/ V+), usually expressed in mV/V, is known as line regulation.
EENG341 ELECTRONICS I FALL08 11
c. Find the change in Vo resulting from connecting a load resistance RL that
draws a current IL of 1mA, and hence find the load regulation (∆Vo/∆ IL),
in mV/mA.
d. Find the change in when 2O LV R k= Ω
EENG341 ELECTRONICS I FALL08 12
e. Find the change in when 0.5O LV R k= Ω
f. What is the minimum value of RL for which the diode still operates in the
breakdown region?
EENG341 ELECTRONICS I FALL08 13
Rectifiers
1. For the circuit below (Half-Wave Rectifier),
Draw the piecewise-linear model circuit.
Draw the i-v transfer characteristic.
Draw the input and output waveforms.
What is the Peak-Inverse Voltage (PIV) across the diode?
EENG341 ELECTRONICS I FALL08 14
2. For the circuit below (Full-Wave Rectifier), use the constant-voltage drop model.
Draw the i-v transfer characteristic.
Draw the input and output waveforms.
What is the Peak-Inverse Voltage (PIV) across the diodes?
EENG341 ELECTRONICS I FALL08 15
3. For the circuit below (Bridge Rectifier), use the constant-voltage drop model.
Draw the i-v transfer characteristic.
Draw the input and output waveforms.
What is the Peak-Inverse Voltage (PIV) across the diode?
EENG341 ELECTRONICS I FALL08 16
4. For the circuit below (Peak Rectifier), use the constant-voltage drop model.
Draw the input and output waveforms.
5. For the circuit below (Half-Wave Peak Rectifier with Load), use the constant-
voltage drop model.
Draw the input and output waveforms.
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