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In radio receivers, RF amplifiers are included at the front end primarily to achieve which of the following benefits?

Difficulty: Easy

Correct Answer: All of the above

Explanation:


Introduction / Context:
Radio frequency (RF) amplifiers are often used as the first stage in radio receivers. Their purpose extends beyond amplification; they also contribute to selectivity, sensitivity, and interference suppression, making them a critical part of the receiver design.


Given Data / Assumptions:

  • RF amplifier stage placed before the mixer.
  • Connected directly to antenna input.
  • Operates at the frequency being tuned, not at IF.


Concept / Approach:
RF amplifiers provide gain to weak signals but also serve additional roles. They improve image frequency rejection by filtering, reduce adjacent channel interference, and isolate the local oscillator to prevent radiation back through the antenna.


Step-by-Step Solution:

Improved image frequency rejection → achieved by RF stage selectivity.Improved adjacent rejection → due to tuned RF filters.Prevent oscillator radiation → RF stage provides isolation between antenna and mixer/oscillator.


Verification / Alternative check:

Receiver design texts confirm the three standard purposes of RF amplifiers.


Why Other Options Are Wrong:

Options (a), (b), and (c) are individually true but incomplete; the correct answer must be 'all of the above'.


Common Pitfalls:

Believing RF amplifiers exist only to increase sensitivity—ignores their key role in selectivity and LO isolation.


Final Answer:

All of the above
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