QUESTIONS Marks 1. (a) What is an amplifier? [1] (b) Consider a series cascade of three amplifiers having gains A., Az a

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Questions Marks 1 A What Is An Amplifier 1 B Consider A Series Cascade Of Three Amplifiers Having Gains A Az A 1 (205.62 KiB) Viewed 31 times

QUESTIONS Marks 1. (a) What is an amplifier? [1] (b) Consider a series cascade of three amplifiers having gains A., Az and A; [4] respectively. Show that overall gain A for the amplifier cascade is given by the product of the individual gains. (c) Three amplifier stages having gains of 5, 10 and 50 and phase shift between input [3] and output signals of 60° each are cascaded. How much is the overall gain and phase shift of the three-stage amplifier? 2. (a) What is feedback? [1] (b) State three advantages of feedback. [3] (c) Show that the gain of an amplifier with feedback is given by [10] А G= 1-BA (d) Use this equation to describe the two basic types of feedback. [4) 3. (a) What is frequency response of an amplifier? [2] (b) Describe the term decibel. Support your answer with basic expression(s) defining (4) the decibel. (e) Show that low frequency response of an amplifier is given by: G = 1-; 1 where fi , and the symbols have their usual meaning. 2TC Ri (d) Sketch frequency response of the amplifier, from low frequency (LF) to high [9] frequency (HF). Among other things, the graph should show the following features: lower and upper cut-off frequencies, corner points, mid-frequency gain, slope in LF and HF region, and amplifier bandwidth. = 19]