Chapter 3

Diode load line

• Forward bias occurs when the P-type semiconductor material is connected to the positive terminal of a battery and the N-type semiconductor material is connected to the negative terminal, as shown below. This usually makes the p–n junction conduct. <ref> Wikipedia P-N junction</ref>
  • Will the current always flow from the anode to the cathode when the diode is forward biased?
• Because diodes are a nonlinear device, traditional circuit analysis will not work on them. One method of analyze the diodes is to do it graphically. This technique is called Load-line analysis.
  • Load-line is only used for dc analysis?
• In circuits with multiple diodes, it is not immediately apparent which diodes are on or off. The ideal-diode model assumes that the diode is a perfect conductor with zero voltage drop in the forward direction and an open circuit in the reverse direction.
  • Is there a better, less exhaustive method to determine which diodes are on or off? With the current system, for n diodes there are $2^{n}$ possibilities.

1. Assume a set of states for the diodes
2. Solve the circuit to find $i_{D}$ for diodes assumed to be on and $v_{D}$ for diodes assumed to be off
3. Check to see if $i_{D}$ is positive for all diodes assumed to be on and if $v_{D}$ is negative for all diodes assumed to be off.

References

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