Describe qualitatively the operation of the circuit in Fig. 3.3. What is the purpose of R1, R2 and the diodes? What is the purpose of the Darlington connections?

a) With the aid of illustrations and using Silicon, describe what an intrinsic semiconductor material is. (b)  With the aid of illustrations and using Silicon, describe what an extrinsic N type            semiconductor material is. (c)  With the aid of illustrations and using Silicon, describe what an extrinsic P type         semiconductor material is. (d)  With the aid of illustrations, describe what happens when P and N materials are        joined/fused together and what is formed across the join. Then describe and        illustrate how the formation at the junction can be controlled. (e)   Give clear illustrations of characteristics for GERMANIUM and SILICON DIODES and          say what is the threshold value (Vt) for Silicon and Germanium.

1. Find the values of I and V in the circuit shown below for the following cases: (i) Assuming the diodes to be ideal. (ii) Assuming the diodes to be non-ideal [Hints: use constant voltage drop model with VDO=0.7 V]. (iii) Assuming the diodes to be non-ideal and use 20k instead of 10k [Hints: use constant voltage drop model with VD=0.7 V]. (iv) Assuming the diodes to be non-ideal and use 5k instead of 10k0 [Hints: use constant voltage drop model with VDO=0.7 V]. tu D₁ Z ² B 5 ΚΩ - 10 V + 10 V 10 ΚΩ ID2 D₂ O + ||

Q2. For the circuit shown, determine whether the diodes in the circuit shown are ON or OFF assuming ideal diode models and calculate the 10V source current? D₁ D2 10Ω. 10V + Is 10Ω ON OFF Is (A) = D2 ON OFF