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Basic Diode Problem

  • #1
658
2

Homework Statement



v1 is a sine wave with amplitude ±10V and the diodes are ideal. Vo is 3V. My question is: will iB always 0?

The Attempt at a Solution



D1 will only be shorted when v1 < 0, which means that the voltage at Va would be from 0 to -10V and D2 would act as an open. Is that correct?

Thanks.
 

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Answers and Replies

  • #2
gneill
Mentor
20,792
2,770
The current source I will not be denied; it will drive the voltage of the Va node to what ever value is necessary so that there is a viable destination for its current.

For D2 to conduct, Va would have to reach 3V. But if V1 is lower than 3V the current will flow via D1, clamping Va to whatever value V1 has. When V1 hits exactly 3V then both paths will conduct. When V1 exceeds 3V, Va will be pegged at 3V by Vo=3V via D2, and current will flow through D2 while D1 is cut off.
 
  • #3
658
2
Thanks for the help, it immediately clicked when you described it like that.
 

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