Re: Measuring Noise Figure

Derek Kozel <derek.kozel@...>

There are different approaches to measuring noise figure. I always use a y factor test and leave the noise source attached to the input of the amplifier/receiver. Powering on and off the noise source provides the change in stimulus to calculate the noise figure but keeps the termination as close as possible, including reducing thermal changes in the short term.

On Mon, Jul 18, 2016 at 7:09 AM, richard@... [ukmicrowaves] <ukmicrowaves@...> wrote:

Hi all

I watched a Youtube video recently about measuring noise figure using the measured gain of an amplifier and a spectrum analyser. The thing that I found odd was that the video maker did not terminate the input of the amplifier - he said it did not matter. I can think of two reasons why it might matter:

1) the input load resistor provides the base thermal noise level (I suppose it might not matter much if the amplifier is very noisy)

2) some amplifiers are not entirely stable when un-terminated.

Would you agree?

73 Richard G3CWI

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