AdvancedA-006-003-003
How much gain should be used in the RF amplifier stage of a receiver?
D
Answer
Propagation and operating practice
Type
A
As much gain as possible, short of self-oscillation
B
It depends on the amplification factor of the first IF stage
C
Sufficient gain to keep weak signals below the noise of the first mixer stage
D
Sufficient gain to allow weak signals to overcome noise generated in the first mixer stage
Answer Notes
The RF amplifier sits at the very front of the receiver, right after the antenna. Its primary job is to boost weak incoming signals just enough so that they are not lost in the inherent electrical noise generated by the subsequent stage, which is usually the first mixer. Mixers are notoriously noisy components.
However, adding too much gain in the RF stage can overload the mixer, leading to cross-modulation and intermodulation distortion. Therefore, the gain must be carefully balanced: enough to overcome mixer noise, but not so much that it compromises the receiver's dynamic range.
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Which of the following is a purpose of the first IF amplifier stage in a receiver?
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What is the primary purpose of an RF amplifier in a receiver?