Transistors

Question 1

At what voltage does a bipolar transistor start conducting?

Answer 1

0.7V

Question 2

What are the features of a class A amplifier?

Answer 2

Good linearity and fidelity. Transistor always on so low efficiency. Features a single transistor operating in the middle of its linear region.

Question 3

What are the features of a class B amplifier?

Answer 3

Higher efficiency than class A, at the cost of some fidelity at low amplitudes. This is because it uses two transistors in a push-pull configuration. There is some switching cost in accuracy when one turns on and the other off, but this is compensated for by improved efficiency.

Question 4

What is a class AB amplifier?

Answer 4

Similar to a class B but biased so that at the switchover point both transistors are on, meaning that the linearity at the switching point is not so effected.

Question 5

What is a class C amplifier?

Answer 5

Uses a single transistor, heavily biased to be hovering on the edge of operating point. Therefore significant distortion, it good efficiency since the transistor is almost always off.