Question 6A496

Shielding between RF amplifier stages serves multiple critical functions to ensure proper circuit operation and performance. **A) Prevents electromagnetic coupling:** Shielding, typically a conductive enclosure, acts to contain or block stray magnetic fields generated by currents in one stage from inducing currents in an adjacent stage. This prevents unwanted signal transfer through inductive coupling, which is particularly important at higher RF frequencies. **B) Prevents electrostatic coupling:** The conductive shield provides a path for stray electric fields to terminate, preventing them from capacitively coupling signals from one stage to another. This minimizes unwanted signal transfer via parasitic capacitance. **C) Improves the overall stability of a receiver:** By preventing both electromagnetic and electrostatic coupling, shielding eliminates unwanted feedback paths between amplifier stages. Such feedback, especially positive feedback, can cause oscillations, spurious signals, and instability, degrading receiver performance. A stable receiver is essential for accurate and reliable signal reception. Since shielding accomplishes all these beneficial effects, "All of the above" is the correct choice.