STUPIDSID
1 (a)
Design two stage RC coupled CE amplifier for the following specifications:
Av ≥ 1600, Vo = 3.2V. Use BC 147A transistor from data sheet. (Assume for BJT hre = hoe =0)
Av ≥ 1600, Vo = 3.2V. Use BC 147A transistor from data sheet. (Assume for BJT hre = hoe =0)
15 M
1 (b)
For the above designed amplifier find voltage gain, input impedance, o/p impedance and total current by Vcc.
5 M
2 (a)
Design class A transformer coupled power amplifier with the following specifications:
Peak O/p Voltage = 6V, Load Resistance RL = 6Ω and VCC = 20V.
Peak O/p Voltage = 6V, Load Resistance RL = 6Ω and VCC = 20V.
10 M
2 (b)
For dual i/p balanced o/p differential amplifier analyze and derive the expression for
(i) differential mode gain
(ii) common mode gain
(iii) CMRR.
(i) differential mode gain
(ii) common mode gain
(iii) CMRR.
10 M
3 (a)
A three stage RC coupled amplifier uses FET with the following parameters:
gm = 2.6 mA/V; rd = 7.7 kΩ, RD = 12kΩ and RG = 1MΩ, Coupling Capacitor is Cc = 0.005 μF and Cs = ∞. Evaluate -
(i) The overall mid-band voltage gain in dB.
(ii) Lower 3dB frequency of individual stages.
(iii) Overall lower 3dB frequency of amplifier.
gm = 2.6 mA/V; rd = 7.7 kΩ, RD = 12kΩ and RG = 1MΩ, Coupling Capacitor is Cc = 0.005 μF and Cs = ∞. Evaluate -
(i) The overall mid-band voltage gain in dB.
(ii) Lower 3dB frequency of individual stages.
(iii) Overall lower 3dB frequency of amplifier.
10 M
3 (b)
Discuss Darlington pair. What are its primary features? Obtain expression for Av, Ai, Ri.
10 M
4 (a)
For the amplifier shown in figure, derive the expression Avf, Aif, Rif and Rof using negative feedbak approach.
12 M
4 (b)
Explain the principle of working of Wein bridge oscillator circuit. Explain why negative feedback in addition to the usual positive feedback is employed in Wein bridge oscillator.
8 M
5 (a)
An amplifier with negative feedback has an overall gain of 100. Variation of this gain of only (+-)1 percent can be tolerated for some specific use. If the open loop gain variations of +10% are expected owin to production spreads in device charactersitics, determie the minimum value of the feedback fraction B and also open loop gain to satisfy the above condition.
10 M
5 (b)
Explain the practical cascade amplifier and derive the expression for Av, Ri, Ro. List application of cascade amplifier.
10 M
6 (a)
Explain why a voltage amplifier cannot be used as a good power amplifier.
8 M
6 (b)
With neat sketch, explain the working of an astable multivibrator. On what factors does the frequency of the output waves depend?
12 M
Write short notes on (any two):
7 (a)
Crystal osciallator and its application.
10 M
7 (b)
Explain low frequency response of RE coupled CE amplifier.
10 M
7 (c)
Harmonic distortions in a power amplifier and prove that P = (1+D2)P1.
10 M
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