WorksheetsPlacement Practice Test 1
Total questions: 100
Worksheet time: 1hrs 12mins
Name
Class
Date
1.
In a common-emitter BJT amplifier, which parameter primarily controls voltage gain?
a)
Collector resistor (RC)
b)
Emitter resistor (RE)
c)
Base bias resistor
d)
Coupling capacitor
2.
The −3 dB cutoff frequency of an RC low-pass filter is given by:
a)
fc = 1/(2πRC)
b)
fc = RC/2π
c)
fc = 2πRC
d)
fc = 1/(RC)
3.
Which amplifier configuration provides the highest input impedance?
a)
Common-emitter
b)
Common-base
c)
Common-collector (emitter follower)
d)
Darlington pair
4.
In op-amp inverting configuration, the closed-loop gain is:
a)
−RF/Rin
b)
1 + RF/Rin
c)
RF/Rin
d)
−(1 + RF/Rin)
5.
For ideal op-amp, input bias current is considered:
a)
Zero
b)
Infinite
c)
Equal to input offset current
d)
Equal to slew rate
6.
The main cause of crossover distortion in class B push-pull amplifiers is:
a)
Saturation
b)
Cutoff near zero crossing
c)
Thermal runaway
d)
Miller effect
7.
Slew rate of an op-amp is defined as:
a)
Max dVout/dt
b)
Gain-bandwidth product
c)
Input offset voltage
d)
Power bandwidth
8.
The dominant pole in an op-amp determines:
a)
Input bias current
b)
Offset voltage
c)
Low-frequency gain
d)
Frequency response/roll-off
9.
In a MOSFET small-signal model, transconductance gm is proportional to:
a)
VDS
b)
(VGS − VT)
c)
Channel length
d)
Gate oxide thickness
10.
A Wien-bridge oscillator requires loop gain of:
a)
1
b)
3
c)
1/3
d)
2
11.
The quality factor Q of a series RLC at resonance is:
a)
Q = ω0L/R
b)
Q = R/ω0L
c)
Q = 1/(ω0CR)
d)
Q = R·C/L
12.
The Miller effect in amplifiers increases:
a)
Input resistance
b)
Input capacitance
c)
Output capacitance
d)
Slew rate
13.
In a differential amplifier, common-mode gain should be:
a)
High
b)
Low
c)
Equal to differential gain
d)
Zero for practical circuits
14.
For an ideal integrator using op-amp, the output for a constant input is:
a)
Constant
b)
Ramp
c)
Sinusoid
d)
Impulse
15.
The bandwidth of a feedback amplifier with negative feedback generally:
a)
Decreases
b)
Increases
c)
Remains same
d)
Becomes infinite
16.
The input signal phase shift through a non-inverting op-amp stage is:
a)
0°
b)
90°
c)
180°
d)
−90°
17.
At resonance, impedance of a parallel RLC circuit is:
a)
Minimum
b)
Maximum
c)
Equal to R
d)
Purely capacitive
18.
A BJT operating in active region has:
a)
Base-collector junction forward biased
b)
Base-emitter junction reverse biased
c)
Both junctions forward biased
d)
BE forward, BC reverse
19.
The GBW (gain-bandwidth product) of an op-amp is:
a)
Constant for a given device
b)
Equal to DC gain
c)
Inverse of slew rate
d)
Independent of temperature
20.
In a source follower (common-drain) MOSFET stage, voltage gain is approximately:
a)
−gm·RD
b)
≈1
c)
>1
d)
0
21.
An active RC filter uses:
a)
Resistors and capacitors only
b)
Resistors, capacitors, and op-amps
c)
Inductors
d)
Transformers
22.
Thermal runaway in BJTs is mitigated by:
a)
Increasing VCE
b)
Decreasing RC
c)
Emitter degeneration (RE)
d)
Removing heat sink
23.
The condition for oscillation (Barkhausen) is:
a)
|Aβ| < 1 and 0° phase shift
b)
|Aβ| = 1 and 0°/360° phase shift
c)
|Aβ| > 1 and 180° phase shift
d)
Aβ = 0
24.
For a BJT, small-signal transconductance gm at room temperature is approximately:
a)
gm = IC/VT
b)
gm = VT/IC
c)
gm = β/IC
d)
gm = IC·VT
25.
In a silicon PN junction at room temperature, typical built-in potential is:
a)
≈0.2 V
b)
≈0.7 V
c)
≈1.5 V
d)
≈2.2 V
26.
Mobility μ relates drift velocity vd to electric field E as:
a)
vd = μE
b)
vd = E/μ
c)
μ = vd·E
d)
vd = μ/E
27.
The Fermi level in intrinsic semiconductor lies:
a)
Near conduction band
b)
Near valence band
c)
Mid-gap
d)
Outside the bandgap
28.
Donor doping in silicon creates:
a)
p-type material
b)
n-type material
c)
Insulator
d)
Metal
29.
The depletion region width in a PN junction increases when:
a)
Forward biased
b)
Reverse biased
c)
Temperature increases
d)
Light increases
30.
Avalanche breakdown occurs due to:
a)
Thermal runaway
b)
Impact ionization
c)
Tunneling
d)
Recombination
31.
Zener breakdown is dominant in:
a)
Heavily doped junctions (low Vz)
b)
Lightly doped junctions
c)
Schottky diodes
d)
LEDs
32.
A Schottky diode is formed between:
a)
Metal and semiconductor
b)
Two semiconductors
c)
Two metals
d)
p and p+ regions
33.
In MOS capacitor, strong inversion occurs when surface potential is:
a)
= 0
b)
≈ ψF
c)
≈ 2ψF
d)
> 3ψF
34.
Channel length modulation in MOSFET causes:
a)
Decrease in drain current with VDS
b)
Finite output resistance
c)
Zero output resistance
d)
Higher threshold
35.
Subthreshold slope ideally at 300 K is:
a)
≈60 mV/dec
b)
≈120 mV/dec
c)
≈30 mV/dec
d)
≈240 mV/dec
36.
In LEDs, emitted photon energy primarily depends on:
a)
Bias current
b)
Bandgap energy
c)
Lifetime
d)
Series resistance
37.
A JFET is normally:
a)
Enhancement-type
b)
Depletion-type
c)
Unipolar with gate forward bias
d)
Bipolar
38.
In Hall effect, Hall voltage is proportional to:
a)
Magnetic field and current
b)
Temperature only
c)
Doping only
d)
Thickness only
39.
The main recombination mechanism in direct bandgap semiconductors is:
a)
Radiative
b)
Auger
c)
Shockley-Read-Hall
d)
Tunneling
40.
The threshold voltage of MOSFET increases with:
a)
Positive body effect coefficient
b)
Decreasing substrate bias
c)
Increasing oxide thickness reduces Vth
d)
Higher temperature always reduces Vth
41.
SOI (silicon-on-insulator) helps primarily by:
a)
Increasing junction capacitance
b)
Reducing parasitics and leakage
c)
Lowering mobility
d)
Increasing body effect
42.
In a PIN diode, the intrinsic region helps with:
a)
High-speed switching
b)
High capacitance
c)
No depletion
d)
Lower breakdown
43.
The transconductance parameter k' (μnCox) depends on:
a)
Oxide capacitance and mobility
b)
Threshold voltage
c)
Channel length only
d)
Drain voltage
44.
Gate oxide scaling mainly reduces:
a)
Cox
b)
Gate leakage
c)
Gate control over channel
d)
Threshold variability
45.
Tunnel diodes exhibit:
a)
Negative differential resistance
b)
Only forward conduction
c)
No quantum effects
d)
High turn-on voltage
46.
Carrier concentration in intrinsic semiconductor varies with temperature approximately as:
a)
ni ∝ T2·e−Eg/2kT
b)
ni ∝ eEg/kT
c)
ni independent of T
d)
ni ∝ 1/T
47.
A varactor diode is primarily used for:
a)
Rectification
b)
Voltage-controlled capacitance
c)
Light emission
d)
Temperature sensing
48.
The Thevenin equivalent resistance is found by:
a)
Shorting all independent sources
b)
Zeroing independent sources (V→0, I→∞)
c)
Open-circuiting the load only
d)
Using KCL only
49.
In AC, complex power S is:
a)
P + jQ
b)
V·I
c)
|V||I|
d)
P − jQ
50.
For a series RL, phase of impedance Z is:
a)
tan-1(Xc/R)
b)
tan-1(Xl/R)
c)
tan-1(R/Xl)
d)
0
51.
Superposition applies to:
a)
Linear circuits
b)
Nonlinear circuits
c)
Magnetic circuits only
d)
Digital circuits only
52.
In a two-port, reciprocity implies:
a)
h12 = h21
b)
y12 = y21
c)
A12 = A21
d)
z12 = −z21
53.
Maximum power transfer occurs when:
a)
RL = 0
b)
RL → ∞
c)
RL = Rth
d)
RL = 2Rth
54.
For a capacitor, impedance is:
a)
Zc = 1/(jωC)
b)
Zc = jωC
c)
Zc = 1/C
d)
Zc = j/C
55.
Quality factor Q of an inductor with series resistance R at ω is:
a)
Q = ωL/R
b)
Q = R/ωL
c)
Q = ωC/R
d)
Q = R/ωC
56.
Node-voltage method primarily uses:
a)
KVL
b)
KCL
c)
Superposition
d)
Norton equivalents
57.
In phasor notation, differentiation corresponds to:
a)
Multiplication by jω
b)
Division by jω
c)
Addition of jω
d)
Subtraction of jω
58.
Bode magnitude slope of a first-order pole is:
a)
−10 dB/dec
b)
−20 dB/dec
c)
+20 dB/dec
d)
0 dB/dec
59.
Routh-Hurwitz stability criterion determines:
a)
Exact pole locations
b)
Number of RHP poles
c)
Gain margin
d)
Phase margin
60.
For a lossless transmission line, characteristic impedance Z0 is:
a)
√(L/C)
b)
√(R/G)
c)
L/C
d)
R/G
61.
Time constant τ of an RC circuit is:
a)
R/C
b)
RC
c)
1/RC
d)
C/R
62.
Power factor is defined as:
a)
Q/P
b)
P/Q
c)
cos(φ)
d)
sin(φ)
63.
In Norton’s theorem, the Norton resistance equals:
a)
Load resistance
b)
Thevenin resistance
c)
Zero
d)
Infinite
64.
Mutual inductance couples coils via:
a)
Electric field
b)
Magnetic field
c)
Thermal field
d)
Acoustic field
65.
In a parallel RLC at resonance, current through the inductor and capacitor is:
a)
Minimum
b)
Maximum and equal/opposite
c)
Zero
d)
Unrelated
66.
For a stable LTI system, impulse response h(t) must be:
a)
Absolutely integrable
b)
Square integrable
c)
Periodic
d)
Noncausal
67.
For maximum power transfer in AC with reactive source impedance, load must:
a)
Equal magnitude only
b)
Conjugate-match the source
c)
Be purely resistive
d)
Be purely reactive
68.
A two-port’s determinant Δ for ABCD parameters is:
a)
A·D − B·C
b)
A + D
c)
A/D
d)
A − D
69.
Skin effect causes AC resistance of a conductor to:
a)
Decrease with frequency
b)
Increase with frequency
c)
Remain constant
d)
Become zero
70.
The canonical SOP form uses:
a)
Maxterms
b)
Minterms
c)
K-maps only
d)
Don’t cares only
71.
A 2:1 multiplexer can implement:
a)
XOR only
b)
Any 2-input boolean function
c)
Full adder
d)
Decoder
72.
Propagation delay of a CMOS inverter primarily depends on:
a)
Gate oxide thickness only
b)
Load capacitance and drive strength
c)
Power supply ripple
d)
Input frequency only
73.
Hazards in combinational logic are removed by:
a)
Increasing VDD
b)
Adding redundant terms / proper synchronization
c)
Reducing temperature
d)
Changing logic family
74.
A JK flip-flop toggles when:
a)
J=0, K=0
b)
J=1, K=0
c)
J=0, K=1
d)
J=1, K=1
75.
Setup time is the minimum time data must be stable:
a)
After the clock edge
b)
Before the clock edge
c)
During the clock edge
d)
Irrelevant
76.
A 4-bit ripple counter’s maximum count is:
a)
4
b)
8
c)
15 (0 to 15)
d)
16 (0 to 15 inclusive)
77.
Two’s complement of a binary number is obtained by:
a)
Inverting bits only
b)
Inverting and adding 1
c)
Adding 1 only
d)
Subtracting 1
78.
The Boolean theorem X + X·Y simplifies to:
a)
X·Y
b)
X
c)
Y
d)
X + Y
79.
Glitches in asynchronous inputs to a synchronous system are avoided by:
a)
Directly feeding combinational logic
b)
Using two-stage synchronizer
c)
Raising VDD
d)
Lowering clock frequency
80.
The fan-out of a logic gate indicates:
a)
How many inputs it can drive
b)
Propagation delay
c)
Noise margin
d)
Power dissipation
81.
De Morgan’s law states that (A·B)’ =:
a)
A’ + B’
b)
A + B’
c)
A’ · B’
d)
A’ + B
82.
Gray code differs from binary in that:
a)
Multiple bits change between successive codes
b)
Only one bit changes between successive codes
c)
All bits change each step
d)
No change
83.
A half-adder outputs:
a)
Sum only
b)
Carry only
c)
Sum and Carry
d)
Difference and Borrow
84.
PLA differs from PAL in that:
a)
PLA has programmable AND and OR arrays
b)
PLA is fixed
c)
PAL is fully programmable
d)
Neither is programmable
85.
The minimal number of flip-flops to design a mod-10 counter is:
a)
3
b)
4
c)
5
d)
10
86.
SR latch is unstable when:
a)
S=R=0
b)
S=1, R=0
c)
S=0, R=1
d)
S=R=1
87.
The carry-lookahead adder speeds up addition by:
a)
Serial carry
b)
Precomputing generate/propagate
c)
Increased fan-out only
d)
Lowering VDD
88.
A synchronous counter advances on:
a)
Asynchronous inputs
b)
Clock edge applied to all flip-flops
c)
Ripple carries only
d)
Random events
89.
Moore machine outputs depend on:
a)
Current state only
b)
Input only
c)
State and input
d)
Clock only
90.
The noise margin high (NMH) in CMOS is:
a)
VOH(min) − VIH(min)
b)
VIH(min) − VOH(min)
c)
VIL(max) − VOL(max)
d)
VOL(max) − VIL(max)
91.
Tri-state buffer enables high-impedance when:
a)
EN=1 in active-high design
b)
EN=0 in active-high design
c)
EN floating
d)
Input=0
92.
An n-bit DAC resolution is:
a)
1/2n of full scale
b)
2n of full scale
c)
n/2 of full scale
d)
1/n of full scale
93.
Metastability in flip-flops is caused by:
a)
Violating setup/hold
b)
Low VDD only
c)
High temperature only
d)
Proper synchronizers
94.
What is the primary function of a voltage follower circuit?
a)
Increase voltage gain
b)
Provide high input impedance
c)
Reduce output impedance
d)
Act as a filter
95.
In a common-source MOSFET amplifier, the phase shift between input and output is:
a)
180°
b)
0°
c)
−90°
d)
90°
96.
The primary purpose of a bypass capacitor in a BJT amplifier is to:
a)
Increase gain
b)
Stabilize biasing
c)
Reduce noise
d)
Improve frequency response
97.
In a common-emitter amplifier, the phase shift between input and output is:
a)
0°
b)
90°
c)
180°
d)
−90°
98.
The primary function of a feedback resistor in an op-amp circuit is to:
a)
Stabilize gain
b)
Increase input impedance
c)
Reduce noise
d)
Control output voltage
99.
In a BJT, the region where the collector current is independent of the base current is known as:
a)
Saturation region
b)
Cut-off region
c)
Active region
d)
Breakdown region
100.
The purpose of a bypass capacitor in a transistor amplifier is to:
a)
Increase gain at high frequencies
b)
Stabilize DC operating point
c)
Reduce power consumption
d)
Improve thermal performance
100 %
