Question 1

A common class of operation used in radio-frequency (RF) amplifier circuits is class-C. Explain what this means, contrasting it against the class-A and class-B operations common in audio-frequency amplifier circuits.


Question 2

Contrast class-A, class-B, and class-C amplifier operations, explaining what defines each class. Then, rank these three classes in order of least power efficiency to greatest power efficiency.


Question 3

Shown here is a schematic diagram for a class-C RF (radio frequency) amplifier circuit:

This circuit will look very strange if you are accustomed to analyzing audio-frequency and DC amplifier circuits. Note some of the distinct differences between this amplifier and an amplifier used to boost audio signals. Also, explain what “class-C” operation means, and how this amplifier is able to output a continuous sine wave despite the transistor’s behavior in class-C mode.

Finally, write an equation that predicts this amplifier’s operating frequency, based on certain component values which you identify.


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