1. A silicon sample is uniformly doped with 10

^{16}phosphorous
atoms / cm

^{3}and 2x 10^{16}boron atoms/cm^{3}. if all the dopants are
fully
ionized, the material is

(a) n-type
with carrier concentration of 10

^{16}/cm^{3}**(b) p-type with carrier concentration of 10**

^{16}/cm^{3}
(c) p-type
with carrier concentration of 2x 10

^{16}/cm^{3}
(d) n-type with carrier concentration
of 2x10

^{16}/cm^{3}
2. An n-type silicon sample, having electron mobility µ

_{n}twice
the hole mobility µ

_{p}, is subjected to a steady illumination such
that the electron concentration doubles from its thermal

equilibrium value. As
a result, the conductivity of the sample

increases by a factor of……….

**Ans : 2**
3. The small signal capacitance of an abrupt P

^{+}N junction is
1 nF/cm

^{2}at zero bias. If the built in voltage is 1 volt, the
capacitance at a reverse bias voltage of 99 volts is equal to …..

**Ans :**0.1 nF /Cm24. Referring to the figure, the switch S is in position 1 initially and

steady state conditions exist from time t=0 to t = t

_{0}. The switch

is suddenly thrown into position 2. The current I flowing through

the 10K resistor as function of time from t=0, is …………

(Give the sketch showing the magnitudes of the current at t=0,

t=t

_{0}and t=∞)

5. Discrete transistors T1 and T2 having maximum collector

current rating of 0.75 Amps are connected in parallel as shown

in the figure.
This combination is treated as a single transistor to

carry a total current of
1 Amp, when biased with self bias

circuit. When the circuit is switched on, T1
draws 0.55 Amps

and T2 draws 0.45 Amps. If the supply is kept on continuously,

ultimately it is very likely that

(a) Both T1
and T2 get damaged

(b) Both T1
and T2 will be safe

**(c) T1 will get damaged and T2 will be safe**

(d) T2 will
get damaged and T1 will be safe

6. The built in potential of the gate junction of an-channel
JFET

is 0.5 volts. The drain current saturates at V

_{DS}= 4.0 volts
when V

_{GS}= 0. The pinch off voltage is ______________**Ans : - 4 volts**
7. In figure, all transistors are identical and have a high
value of

beta (β). The voltage V

_{DC}is equal to _____**Ans : 5 volts**

8. In figure the input V

_{i}is a 100 Hz triangular wave having a
peak to peak amplitude of 2 volts and an average value of

zero
volts. Given that the diode is ideal, the average value

of the output V

_{o}is ______**Ans : 0.3 Volts**
9. In figure, the n-channel MOSFETs are identical and their
current

voltage characteristics are given by the following expressions:

**Ans : 1 mA**

Where are the solutions for remaining answers. Can you please mail me the answer key. Thank you

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