Direct Coupled Class AB Output Stage: The output capacitor in a capacitor-coupled power amplifier is a large expensive component that should be eliminated if possible. Figure 18-23 shows a Class-AB amplifier circuit with a Direct Coupled Class AB Output Stage. In this case, the supply voltages must be positive and negative quantities, +VCC and -VEE as […]
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Capacitor Coupled Class AB Output Stage: The basic circuit of a Class-AB amplifier using a complementary emitter follower output stage and a Capacitor Coupled Class AB Output Stage load is shown in Fig. 18-18. The circuit is termed a complementary symmetry amplifier. Transistor Q1 and resistors R1, R2, RC, and RE1 comprise a common emitter amplifier
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Complementary Emitter Follower Circuit: Two BJTs connected to function as Complementary Emitter Follower Circuit are shown in Fig. 18-17. Although one is npn and the other is prim the devices are selected to have similar parameters, so they are complementary transistors. The circuit is termed a complementary emitter follower. A single-transistor emitter follower is essentially
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Transformer Coupled Amplifier: Transformer Coupled Amplifier commences with the load resistance and output power, specification. A signal voltage amplitude may also be stated, as well as the upper and lower cutoff frequencies for the amplifier. If a supply, voltage is given, then the design must determine a specification for the transformer. Where an available transformer
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Transformer Coupled Class B Amplifier: Class B Amplifier – The inefficiency of Class-A amplifiers is largely due to the transistor bias conditions. In a Class-B amplifier, the transistors are biased to cutoff, so that there is no transistor power dissipation when there is no input signal. This gives the Transformer Coupled Class B Amplifier a
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Transformer Coupled Class A Amplifier: Class A Circuit – Instead of capacitor coupling, a Transformer Coupled Class A Amplifier may be used to ac couple amplifier stages while providing dc isolation between stages. The resistance of the transformer windings is normally very small, so that there is no effect on the transistor bias conditions. Figure
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