Chapter 8 electronics

What defines a power amplifier?

A power amplifier handles large signals and is usually the last stage in the signal processing system.

What is the importance of efficiency in power amplifiers?

Efficiency compares the signal power output to the DC power input and affects the cost and size of the power supply.

How efficient can class A amplifiers theoretically be?

The maximum theoretical efficiency for class A operation is 25 percent, and with transformer coupling, it is 50 percent.

What is the conduction angle of Class B amplifiers?

The conduction angle for Class B amplifiers is 180º.

Why are Class B amplifiers considered more efficient than Class A?

Class B amplifiers do not present a fixed drain on the power supply and draw less current from the supply for smaller signals.

What major drawback do Class A circuits have?

The fixed drain on the power supply leads to poor efficiency when signals are small.

What is crossover distortion in Class B push-pull amplifiers?

Crossover distortion is a distortion that occurs at the transition between the conduction of two transistors and can be eliminated by providing some forward bias for their base-emitter junctions.

What is a complementary symmetry amplifier?

An amplifier that uses a PNP-NPN transistor pair for push-pull operation.

How does the impedance ratio in a transformer-coupled amplifier relate to the turns ratio?

The impedance ratio is equal to the square of the turns ratio.

What is the conduction angle for Class C amplifiers?

The conduction angle for Class C amplifiers is around 90º.

What type of operation is class AB most popular for?

Class AB operation is the most popular for high power audio work.

What advantage do bridged amplifiers have?

Bridged amplifiers quadruple the maximum output power for any given supply voltage and load resistance and eliminate the output coupling capacitor.