Question
Which of the following reduces the likelihood of receiver desensitization?
Answer Options
- A) Insert attenuation before the first RF stage
- B) Raise the receiver’s IF frequency
- C) Increase the receiver’s front-end gain
- D) Switch from fast AGC to slow AGC
Correct Answer: A
Explanation
Receiver desensitization is a result of the front-end stages being overdriven by strong, local, or nearby signals, causing a collapse in the circuit’s dynamic range. To reduce this likelihood, the total power hitting the most sensitive active devices (the first amplifier and mixer) must be reduced.
The most effective way to reduce the likelihood of desensitization is to insert attenuation before the first RF stage. This resistor or attenuator network reduces the amplitude of all incoming signals equally, dropping the strength of the strong interfering signal to a level that the front-end can handle linearly, thereby increasing the receiver’s effective blocking dynamic range.
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