Fourth Semester B.Tech. Degree Examination, December 2009
(2003 Scheme)
03.405 : ELECTRONIC CIRCUITS II (TA)
Time : 3 Hours Max. Marks : 100
PART – A
Answer all questions. (10×4=40 Marks)
1. What is miller output capacitor ? Give its effect on high frequency response.
2. Show that bandwidth of a Common Base amplifier is higher than Common Emitter
amplifier.
3. What is a cascade amplifier ? Give its advantages.
4. Calculate the overall upper 3dB frequency of a FET amplifier having an individual
stage value of f2 = 2 MHz for the case of n = 4 and 6.
5. What are the non-ideal characteristics of a differential amplifier ?
6. Represent the pole zero location of 2-stagggered tuned amplifier.
7. What are the advantages of a crystal oscillator over other Sinusoidal Oscillators ?
8. Draw the four basic feedback topologies in feedback connections of a feedback
amplifiers.
9. Why is positive feedback not used in amplifiers ?
10. What is the significance of pole location on the characteristics of a system ?
PART – B
Answer any two questions from each module. (6×10=60 Marks)
Module – I
11. a) Draw the high frequency equivalent circuit of a BJT. What are its characteristics ?
b)
For the circuit shown compute the upper half-power frequency, assuming that
low frequency amplifier is a CE stage.
12. a) Sketch the frequency response of a MOSFET cs amplifier. Explain the low and
high frequency fall of in gain.
b) A common source FET amplifier utilizes a resistance Rs of 1K?? bypassed by a
capacitor CS. It is found that the pole and zero due to CS are at 100 rad/sec. and
10 rad/sec. respectively. Find the values of CS and gm.
13. Explain the principle of operation of cascode amplifier. With the high frequency
equivalent circuit of a cascode amplifier, derive the expressions for overall uppercut-
off frequency and overall bandwidth.
-3- 8079
Module – II
14. Draw the small signal equivalent circuit of a differential amplifier. Derive its differential
and common mode gain also the CMRR.
15. a) Explain the salient features of atleast three types of current mirror circuit.
b) The p-n-p current mirror in the figure uses transistors with ?? ??150 . For
I 1mA
1
C ?? and VCC = 15V determine the value of R.
16. A Colpitts oscillator is designed with C1 = 100 pF and C2 = 7000 pF. The inductance
is variable.
a) Determine the range of inductance values if the frequency of oscillation is to
vary between 950 and 2050 KHz.
b) Explain how frequency stability can be obtained in the above Colpitts oscillator.
Module – III
17. a) Draw a single BJT amplifier with series-series feedback configuration and derive
its transconductance gain.
b) Illustrate the Bode plot of a multistage amplifier.
18. a) Explain the need of frequency compensation in amplifiers.
b)
For the circuit shown the transistor has gm = 2mS ???? ?? 500?? and very large ??0 .
Calculate the feedback factor, input resistance and voltage gain using feedback
principle.
19. a) Explain the general principles of sweep circuits.
b) Draw the circuit of a miller sweep generator and explain its operation.
————————
8079 -4-
(2003 Scheme)
03.405 : ELECTRONIC CIRCUITS II (TA)
Time : 3 Hours Max. Marks : 100
PART – A
Answer all questions. (10×4=40 Marks)
1. What is miller output capacitor ? Give its effect on high frequency response.
2. Show that bandwidth of a Common Base amplifier is higher than Common Emitter
amplifier.
3. What is a cascade amplifier ? Give its advantages.
4. Calculate the overall upper 3dB frequency of a FET amplifier having an individual
stage value of f2 = 2 MHz for the case of n = 4 and 6.
5. What are the non-ideal characteristics of a differential amplifier ?
6. Represent the pole zero location of 2-stagggered tuned amplifier.
7. What are the advantages of a crystal oscillator over other Sinusoidal Oscillators ?
8. Draw the four basic feedback topologies in feedback connections of a feedback
amplifiers.
9. Why is positive feedback not used in amplifiers ?
10. What is the significance of pole location on the characteristics of a system ?
PART – B
Answer any two questions from each module. (6×10=60 Marks)
Module – I
11. a) Draw the high frequency equivalent circuit of a BJT. What are its characteristics ?
b)
For the circuit shown compute the upper half-power frequency, assuming that
low frequency amplifier is a CE stage.
12. a) Sketch the frequency response of a MOSFET cs amplifier. Explain the low and
high frequency fall of in gain.
b) A common source FET amplifier utilizes a resistance Rs of 1K?? bypassed by a
capacitor CS. It is found that the pole and zero due to CS are at 100 rad/sec. and
10 rad/sec. respectively. Find the values of CS and gm.
13. Explain the principle of operation of cascode amplifier. With the high frequency
equivalent circuit of a cascode amplifier, derive the expressions for overall uppercut-
off frequency and overall bandwidth.
-3- 8079
Module – II
14. Draw the small signal equivalent circuit of a differential amplifier. Derive its differential
and common mode gain also the CMRR.
15. a) Explain the salient features of atleast three types of current mirror circuit.
b) The p-n-p current mirror in the figure uses transistors with ?? ??150 . For
I 1mA
1
C ?? and VCC = 15V determine the value of R.
16. A Colpitts oscillator is designed with C1 = 100 pF and C2 = 7000 pF. The inductance
is variable.
a) Determine the range of inductance values if the frequency of oscillation is to
vary between 950 and 2050 KHz.
b) Explain how frequency stability can be obtained in the above Colpitts oscillator.
Module – III
17. a) Draw a single BJT amplifier with series-series feedback configuration and derive
its transconductance gain.
b) Illustrate the Bode plot of a multistage amplifier.
18. a) Explain the need of frequency compensation in amplifiers.
b)
For the circuit shown the transistor has gm = 2mS ???? ?? 500?? and very large ??0 .
Calculate the feedback factor, input resistance and voltage gain using feedback
principle.
19. a) Explain the general principles of sweep circuits.
b) Draw the circuit of a miller sweep generator and explain its operation.
————————
8079 -4-
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