Q1.In a forward biased pn junction diode, the sequence of events that best describes the mechanism of current flow is
Answer : Option AExplaination / Solution:
The potential barrier of the pn junction is lowered when a forward bias voltage is applied, allowing electrons and holes to flow across the space charge region (Injection) when holes flow from the p region across the space charge region into the n region, they become excess minority carrier holes and are subject to diffuse, drift and recombination processes.
Hence correct option is (A)
Q2.In IC technology, dry oxidation (using dry oxygen) as compared to wet oxidation (using steam or water vapor) produces
Answer : Option DExplaination / Solution:
In IC technology, dry oxidation as compared to wet oxidation produces superior quality oxide with a lower growth rate
In a MOSFET operating in the saturation region, the channel length modulation effect causes
Answer : Option DExplaination / Solution:
In a MOSFET operating in the saturation region, the channel length modulation effect causes a decrease in output resistance.
Q4.In the circuit shown below, capacitors C1 and C2 are very large and are shorts
at the input frequency. vi is a small signal input. The gain magnitude at 10
M rad/s is
Answer : Option AExplaination / Solution:
For the parallel RLC circuit resonance frequency is,
Thus given frequency is resonance frequency and parallel RLC circuit has
maximum impedance at resonance frequency
Gain of the amplifier is where ZC is impedance of parallel RLC
circuit.
Q7.A silicon PN junction is forward biased with a constant current at room temperature. When the temperature is increased by 10ºC, the forward bias voltage across the PN junction
Answer : Option DExplaination / Solution:
For every 1º C increase in temperature, forward bias voltage across diode decreases by 2.5 mV. Thus for 10º C increase, there us 25 mV decreases
Q9.For a BJT the common base current gain α = 0.98 and the collector base
junction reverse bias saturation current ICO = 0.6 μA. This BJT is connected in
the common emitter mode and operated in the active region with a base drive
current IB = 204 A. The collector current IC for this mode of operation is
Answer : Option DExplaination / Solution:
In active region, for common emitter amplifier,
Substituting ICO = 0.6 μA and IB = 204 μA in above eq we have,
Q10.For the BJT QL in the circuit shown below, The
switch is initially closed. At time t = 0, the switch is opened. The time t at
which Q1 leaves the active region is
Answer : Option CExplaination / Solution:
Applying KCL at collector
with time, the capacitor charges and voltage across collector changes from 0
towards negative.
Total Question/Mark :
Scored Mark :
Mark for Correct Answer : 1
Mark for Wrong Answer : -0.5
Mark for Left Answer : 0