In load-line analysis, what is a consequence of choosing the Q-point near saturation?

• A. Output swing is limited and distortion increases.
• B. Output swings expand symmetrically.
• C. The transistor operates with infinite gain.
• D. The power supply becomes unstable.

Answer: (A)

The main idea is that the Q-point sets how much headroom the amplifier has to swing before hitting the transistor’s limits. When the Q-point is near saturation, the device is already pushing toward its maximum collector current for the given load, so there isn’t much room to drive the output higher. If the input causes the transistor to work harder, it can’t increase current much and the collector-emitter voltage drops to a low saturation value. The result is clipping of the positive half of the waveform, so the output swing is limited and distortion increases. The negative swing is bounded by cutoff, but the dominant practical effect of biasing near saturation is reduced, distorted output. The other ideas—swings expanding, infinite gain, or power-supply instability—don’t describe what happens when you push the transistor into saturation.