1. For the circuit shown in the following figure, transistors
M1 and

M2 are identical nMOS transistors. Assume that M2 is in

saturation and the output is unloaded . The current I

_{x}is related
to I

_{bias}as
2. The measured transconductance g

_{m}of an NMOS transistor
operating
in the linear region is plotted against the gate voltage

V

_{G}at constant drain voltage V_{D}. Which of the following figures
represents
the expected dependence of g

_{m}on V_{G}?
3. Two identical NMOS transistors M1 and M2 are connected as

shown below. V

_{bias}is chosen so that both transistors are in
saturation. The equivalent g

_{m}of the pair is defined to be
(dI

_{out}/ dV_{i}) at constant V_{out}. The equivalent g_{m}of the pair is
4. Silicon is doped with boron to a concentration of 4 x 10

^{17}
atoms /cm

^{3}. Assuming the intrinsic carrier concentration of
silicon
to be 1.5 x 10

^{10}/ cm^{3}and the value of KT/q to be 25mV
at 300

^{o}K. compared to undoped silicon, the Fermi level of
doped
silicon

5. The cross section of a JFET is shown in the following figure.

Let V

_{G}be -2 volts and let V_{p}be the initial pinch off voltage.
If the width W is doubled (with
other geometric parameters

and doping levels remaining the same), then the
ratio between

the mutual transconductance of the initial and the modified

JFET
is

6. Consider the following assertions.

S1 :
For Zener effect to occur, a very abrupt junction is

required

S2 :
For quantum tunneling to occur, a very narrow

energy barrier is required .

Which of the following is correct ?

(A)
Only S2 is true

(B)
S1 and S2 are both true but S2 is not a reason
for S1

(C)
S1 and S2 are both true but S2 is a reason for S1

(D)
Both S1 and S2 are false

## No comments:

## Post a Comment