- Ra 1 2 K C H 100 Uf Vcc 18 V Re 1692 V B 40 D Explain How Distortion Is Overcome In The Class B Amplifiers E Qu 1 (378 KiB) Viewed 33 times
Ra 1.2 k C₁ #H 100 µF +Vcc (18 V) Re-1692 V₂ B-40 d) Explain how distortion is overcome in the class B amplifiers. e) Qualitatively explain the difference between the contemporary class B and push pull class B. Question (a) What do you understand by feedback? Why negative feedback is applied in high gain amplifiers? (b) Derive an expression for the gain of negative voltage feedback amplifier. (c) When negative voltage feedback is applied to an amplifier of gain 300, the overall gain falls to 90. (i) Calculate the fraction of the output voltage feedback m.. (ii) If this fraction is maintained, calculate the value of the amplifier gain required if the overall stage gain is to be 100. (d) The gain of an amplifier without feedback is 200 whereas with negative voltage feedback it falls to 70. If due to ageing the amplifier gain falls to 90, find the percentage reduction in stage gain (i) without feedback. (ii) with negative feedback. Question a) Define the term oscillator. State any two advantages of electronic oscillators over mechanical oscillators. b) Explain the two types of sinusoidal oscillations. c) What is an oscillatory circuit? Explain the working of a simple oscillatory circuit. d) Figure below shows the Colpitt's oscillator. Determine the (i) operating frequency and (ii) feedback fraction. + Vcc RF CHOKE 0.1 μF C₁ T 1μFC₂₁₂ d , 470ul V₂ e) State the limitations of RC and LC oscillators. Give two advantages of RC over LC oscillators g) Explain why a Piezoelectric crystal oscillator is preferred to other oscillators using an LC and RC oscillatory tank.