Electronic – P-N Diodes in series. Is the solution correct

diodespn-junction

I have attempted to work out a solution on a short question relating to p-n diodes. Is my solution correct?

The question (from a past paper) :
The question:
From the question I understand that there are two parts:

  1. Give the relationship between the reverse saturation currents of the two diodes.

  2. Using the given values, determine the saturation current in diode D2

My attempt:

1.
Attempt at the first part of the question

Does this seem like an appropriately given relationship between the saturation currents? And is it correct?

2.

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Im not sure if it's correct to equate the ideal diode equations this way, or if I have calculated VD1 correctly.
Any advice or help will be greatly appreciated, and if anyone has noticed something terribly wrong with my logic, please let me know.
Many thanks in advance.

Best Answer

The current should be the same as a single diode, the voltage drop will be double that of a single diode. So if the answer for the current is the same for a single diode, then you are on the right track. The current has to be the same for both, because they are in series.