Download EC1-EC6304-SET1 ECE III SEM model

LOYOLA – ICAM
COLLEGE OF ENGINEERING AND TECHNOLOGY (LICET)
Loyola College Campus, Nungambakkam , Chennai – 34
Branch: ECE
Date:15/10/2014
Semester: III
Time: 8.00 – 11.00 am (3Hrs)
MODEL EXAM
ELECTRONIC CIRCUITS-1(EC6304)
Part-A (Answer all the questions)
(10x2=20)
1. Why is temperature compensation required?
2. Briefly discuss about a.c and d.c load line?
3. Draw a BJT Darlington amplifier with Bootstrap arrangement.
4. State Miller's theorem.
5. Draw the small signal equivalent JFET common gate circuit?
6. What is voltage swing limitation??
7. Define the term “sag” related to transistor?
8. Draw the high-frequency equivalent circuit of BJT and FET.
9. What is Widlar current source?
10. Draw the circuit of MOSFET differential amplifier with active load.
Part-B(Answer all the questions)
(5x16=80)
11. (A) (i) Explain the circuit which uses a diode to compensate for changes in VBE.
(8)
(ii) In the transistor shown in the following figure, RC=8KΩ, RL=24KΩ and VCC=24V. Draw
the d.c.load line and a.c. load line. Determine the optimum operating point.
(8)
+VCC
RB
RC
CC
CC
VAC
RL
(OR)
(B) (i) Discuss the Voltage divider feedback bias for FET.
(ii) Explain the collector feedback bias & derive an expression for stability factor.
(8)
(8)
12. (A) Briefly explain the operation of a Darlington emitter follower and derive the necessary
expressions for its performance measures?
(OR)
(B) For the common collector amplifier circuit shown below, the transistor hybrid parameters are
hic=1.2kΩ, hfc=-101, hrc=1 and hoc=25µA/V. The component values are RS=1kΩ, R1=10kΩ,
R2=10kΩ, RE=5kΩ, RL=20kΩ, VCC=22V Calculate the Ri, Ai, Ais, Avs, Ro.
+VCC
R1
RS
CC
CC
VS
R2
RL
RE
13. (A) Determine the small-signal voltage gain, input and output resistances of a common-source
amplifier MOSFET amplifier shown in the figure with the parameters: VDD=3.3V, RD =10kΩ,
R1=140 kΩ, R2=60kΩ, and RSi=4kΩ. The transistor parameters are: VTN = 0.4V, Kn=0.5mA/V2,
and λ=0.02V-1.
+VDD
R1
RD
CC
VO
RSi
Vin
CC
RL
R2
(OR)
(B) Explain the operation of BiMOSCascode amplifier and derive the expression for its
transconductance gain. Also discuss its frequency response qualitatively.
14. (A) Determine the α- and β-cut off frequencies for a transistor with the following specifications.
gm=.038 mho, rb’e=5.9kΩ, hie=6kΩ, rbb’=100Ω, Cb’c=12pF, Cb’e=63pF, fT=80MHz, hfe=224 at
1kHz. Also, calculate the CE chort circuit current gain at the frequencies fα, fβ and fT.
(OR)
(B) Discuss the frequency response of MOSFET CS amplifier.
15. (A) Determine the small-signal voltage gain of the NMOS amplifier with depletion load. For the
circuit shown in the figure, assume transistor parameters of VTND= +0.8V, VTNL= −1.5V, KnD=1
mA/V2, KnL=0.2 mA/V2, and λD= λL= 0.01 V−1. Assume the transistors are biased at IDQ= 0.2mA.
(OR)
(B) (i) Discuss the transfer characteristics of NMOS amplifier with depletion load. Use the small signal
model to derive the expression for its voltage gain.
(10)
(ii) Briefly explain the operation of CMOS common-source amplifier with n-channel enhancementmode driver and a p-channel enhancement mode active load
(6)