1. In abrupt PN junction, the doping concentrations on the
p-side
and n-side are NA = 9 x 1016 /cm3 and ND
= 1 x 1016 /cm3
respectively. The PN junction is reverse
biased and the total
depletion width is 3 µm. The depletion width on the
p-side is
(A) 2.7 µm (B) 0.3 µm
(C) 2.25 µm (D) 0.75
µm
2. The resistivity of a uniformly doped n-type silicon sample
is
0.5 Ω-cm.
If the electron mobility (µn) is 1250 cm2/V-sec and
the charge
of an electron is 1.6 x 10-19 coulomb, the donor
impurity
concentration (ND) in the sample is
3. Consider an abrupt PN junction. Let Vbi be the
built in potential
of this junction and VR be the applied reverse
bias. If the
junction capacitance (Cj) is 1 pF for Vbi +
VR = 1 volt, then for
Vbi + VR = 4 volts, Cj
will be
(A) 4 pF (B) 2 pF (C) 0.25 pF (D) 0.25 pF
4. Consider the following statements S1 and S2.
S1 : The threshold voltage (VT) of a MOS capacitor
decreases with
increase in gate oxide thickness
S2 : The threshold voltage (VT) of a MOS capacitor
decreases with
increase in substrate doping
concentration.
Which one of the following is correct ?
5. The drain of an n-channel MOSFET is shorted to the gate so
that
VGS = VDS. The threshold voltage (VT) of
MOSFET is 1 volt.
If the drain current (ID) is 1 mA for VGS
= 2 volts, then
for VGS = 3 volts, ID is
(A) 2 mA (B) 3 mA
(C) 9 mA (D) 4
mA
6. The longest wavelength that can be absorbed by silicon,
which
has the bandgap of 1.12 eV, is 1.1 µm. If the longest wavelength
that can be absorbed by another material is 0.87 µm, then the
bandgap of this
material is
(A) 1.416 eV (B) 0.886
eV
(C) 0.854 eV (D) 0.706 eV
7. The neutral base width of a bipolar transistor, biased in
the
active region, is 0.5 µm. The maximum electron concentration
and the diffusion
constant in the base are 1014 /cm3 and
Dn = 25
cm2/sec respectively. Assuming negligible
recombination in the base,
the collector current density is
8. Assuming that the β of the transistor is extremely large
and
VBE = 0.7 volts, IC and VCE in the circuit
shown are,
9. In the voltage regulator shown , the load current can vary
from
100 mA to 500 mA. Assuming that the zener diode is ideal
(i.e. the zener
knee current is negligibly small and zener
resistance is zero in the breakdown
region), the value of R is
why old some subjects no signals and systems questions and solutions aare seen
ReplyDelete