Solve Basic Diode Problem: Will iB Always Be 0?

[DrummingAtom]

Homework Statement

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

The Attempt at a Solution

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

Thanks.

 

[gneill]

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.

 

[DrummingAtom]

Thanks for the help, it immediately clicked when you described it like that.