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| SEC. 10-1 VOLTAGE GAIN The voltage gain of a CE amplifier equals the ac collector resistance divided by the ac resistance of the emitter diode. SEC. 10-2 THE LOADING EFFECT OF INPUT IMPEDANCE The input impedance of the stage includes the biasing resistors and the input impedance of the base. When the source is not stiff compared to this input impedance, the input voltage is less than the source voltage. SEC. 10-3 MULTISTAGE AMPLIFIERS The overall voltage gain equals the product of the individual voltage gains. The input impedance of the second stage is the load resistance on the first stage. Two CE stages produce an amplified inphase signal. SEC. 10-4 SWAMPED AMPLIFIER By leaving some of the emitter resistance unbypassed, we get negative feedback. This stabilizes the voltage gain, increases the input impedance, and reduces largesignal distortion. SEC. 10-5 TWO-STAGE FEEDBACK We can feed back the output voltage of the second collector to the first emitter through a voltage divider. This produces negative feedback, which stabilizes the voltage gain of the two-stage amplifier. SEC. 10-6 TROUBLESHOOTING With single- or double-stage amplifiers, start with dc measurements. If they do not isolate the trouble, you continue with ac measurements until you have found the trouble. |