In a transistor biased at the midpoint of its DC load line, if the device’s current gain (beta) increases while base bias remains unchanged, how does the Q-point shift along the load line?

Introduction / Context:The operating point (Q-point) of a transistor is where the device resides on its load line under quiescent (no-signal) conditions. Understanding how changes in current gain affect this point is essential for bias stability and linear amplifier design.

Given Data / Assumptions:

• Transistor initially biased near the midpoint of the load line.
• Base bias is fixed (no change in bias network values).
• Current gain beta increases due to device variation or temperature.

Concept / Approach:Collector current Ic ≈ beta * Ib (for a given base current Ib). If beta rises while Ib is constant, Ic increases. On a load line (defined by Vcc and RC), higher Ic moves the Q-point toward higher current and lower collector-emitter voltage, i.e., up the current axis toward saturation.

Step-by-Step Solution:

Verification / Alternative check:Graphically, draw the same load line and intersect it with the new Ic for the unchanged base current; the intersection is above the previous Q-point.

Why Other Options Are Wrong:

Common Pitfalls:Assuming feedback or emitter degeneration compensates automatically; without such stabilization, beta shifts do move the Q-point.

Final Answer:up.