Electronic – Diode circuit analysis solution

circuit analysisdiodeshomework

I am not familiar with circuit analysis, although I can manage to solve basic circuit. However, I am currently stuck with a problem and I am not sure about the solutions.

If anyone could have a look at my solutions I would highly appreciate it.

By using circuit logic I assumed D1 to be OFF and D2 ON. From there, we KVL and current division rules to find the total current I:

10.7 - I*R1 - 0.7 - 0.25I*R2 - I*R3 = 0 and derive I = 1.08 mA

From here we have the following: 

V1 = 10.7 - R1*I = 4.22V
V2 = V1 - 0.7 = 3.52V
V3 = V2 - 0.25I*3 = 2.71V
V4 = V2 -0.75I*1 = 2.71V

We note that V1 > V4 therefore D1 is indeed reverse biased.

For some reason I am not sure about these results, this is my first problem of the sort.

Here is the problem:
enter image description here

Best Answer

Guess which diodes are conducting. Remove the non-conducting diodes, and replace the conducting diodes with a 0.7V voltage source, + side at the anode. Solve using standard analysis.

Then, verify that your guess was correct. Current should flow into the + side of the simulated conducting diode, if not, it wasn't conducting. Where the non-conducting diode was should have a voltage less than 0.7V (anode V - cathode V), if not it should not have been removed.

For this exercise, it is fairly obvious that current is flowing from top to bottom, so D2 is probably conducting. Replace D2 with a voltage source, then solve. Verify that current is flowing into the anode of D2. Then verify that V4 - V1 is not greater than 0.7V.

If your guesses were wrong (verification didn't work), then make another guess and solve again.

Related Topic