Subelement F: Receivers— Topic 43: Oscillators
Question 3-43F5
Element 3 (GROL)What condition must exist for a circuit to oscillate? It must:
Explanation
For a circuit to oscillate, it must have sufficient positive feedback. This means a portion of the output signal is fed back to the input *in phase*, causing the signal to reinforce itself and grow until it reaches a stable, self-sustaining level. This positive feedback, coupled with a loop gain of at least one, is the fundamental condition for generating a continuous waveform.
Option A is incorrect because a gain of less than 1 would cause any signal to diminish and die out, preventing oscillation. Option B, neutralization, is a technique used to *prevent* unwanted oscillations in amplifiers by canceling internal feedback paths, making it the opposite of what's needed for oscillation. Option C, negative feedback, is used to stabilize amplifiers, reduce distortion, and improve linearity; it generally *prevents* oscillation by feeding the output out of phase with the input.
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