Response to the following
In a particular circuit application, ten "20-mA diodes" (a 20-mA diode is a diode that provides a 0.7-V drop when the current through it is 20 mA) connected in parallel operate at a total current of 0.1 A. For the diodes closely matched, what current flows in each? What is the corresponding small-signal resistance of each diode and of the combination?
Compare this with the incremental resistance of a single diode conducting 0.1 A. If each of the 20-mA diodes has a series resistance of 0.2Ω associated with the wire bonds to the junction, what is the equivalent resistance of the 10 parallel-connected diodes?
What connection resistance would a single diode need in order to be totally equivalent?
(Note: This is why the parallel connection of real diodes can often be used to advantage.)