11Chapter 8Output stages &2:(emitter follower)3 425 6(cont.)7(cont.)839It has high efficiency, It is primarily due to the fact that there is no power drawn by circuit under zero signal conditions.Since in push pull arrangement 180 phase difference exist between even-order harmonics produced by each transistor, they cancel out thereby giving an almost distortion free output. This automatics cancellation of all even order harmonics from the output current makes class push pull amplifier highly desirable for communication sound equipments.Uses: Class B push pull amplifier are extensively used for audio work in portable recorder players, as stereo amplifiers, and in radio receiver.10It, in fact means locating the Q-point of each transistor slightly above the cutoff.So that each one operate more than one half cycle.11 12413Advantage and disadvantage of class AB amplifier1415 16517 1819In such amplifiers, transistor is biased beyond cut-off.20• Output current flows only during a part of the positive half cycle of the input signal.• There is no output current flow during any part of the negative half cycle of the input signal.• Class C amplifier have high circuit efficiency of more than 78%.• They are used as a high frequency power switches in radio and TV transmitters rather than as a
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