Discussion
Why is a stage's noise figure worse when driven from a very low impedance?
Answer: C
A low source resistance generates little thermal noise of its own, so the amplifier's fixed input noise voltage becomes a large fraction of the total and the ratio degrades. Loading and capacitor reactance affect the signal rather than the noise ratio. Noise figure is always a comparison against what the source itself contributes, which is why the same amplifier can look excellent on one source and poor on another. Framing the question as which quantity the change acts upon makes the answer follow without calculation. Framing the question as which quantity the change acts upon makes the answer follow without calculation.
Post your comment
Please log in or register to post a comment.
Examination Categories
- SSC Exams
- Banking Exams
- Teaching Exams
- Civil Services Exams
- Railways Exams
- Engineering Recruitment Exams
- Defence Exams
- State Government Exams
- Police Exams
- Insurance Exams
- Nursing Exams
- Other Government Exams
- NRA CET
- PG Entrance Exams
- Campus Placement
- MBA Entrance Exams
- CUET and UG Entrance
- Judiciary Exams
- Regulatory Body Exams
- Software Development