Problem

Assume each diode in the circuit shown in Figure P1.50 has a cut-in voltage of Vγ = 0.65 V. (a) The input voltage is V1 = 5 V. Determine the value of R1 required such that ID1 is one-half the value of ID2. What are the values of ID1 and ID2? (b) If V1 = 8 V and R1=2 kΩ, determine ID1 and ID2.

Step-by-step solution

1. Step 1 of 6

   (a)

   Given circuit

   

   Comment

2. Step 2 of 6

   Given data,

   

   

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   The output voltage is equal to voltage across diode

   Hence 

   Given that is one half of the value of 

   Then,

   

   

   By applying KCL in above circuit we get,

   

    ………….. (1)

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   From the given circuit  is equal to the sum of currents through  and diode .

   Hence,

   

   But ,

   

   

   By substituting  in Equation (1) we get;

   

   

   

   

   

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   Now the value of  is given by,

   

   

   

   The value of  is given by,

   

   

   

   Comment

3. Step 3 of 6

   (b)

   Given circuit

   

   Comment

4. Step 4 of 6

   Given data,

   

   

   Comment

5. Step 5 of 6

   The output voltage is equal to voltage across diode

   Hence 

   From the given circuit we can write

   

   

   

   Comment

6. Step 6 of 6

   Now applying KCL to the given circuit we have,

   

   

   

   

   Comment