# flicker noise question

1. ## flicker noise question

as we know, flicker noise spectral density is 1/f and its power is ln(f); but when we integrate from a lower end to a higher end, if the lower end tends to approach zero frequency, the total power integrated tends to approach infinity. in razavi's book, it is explained as that this phenomenon is a long term effect due to the extremely low frequency, like aging. so my question is, in real design or calculation, what is the lower end of the frequency to choose?

c.m.

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2. ## Re: flicker noise question

hi,
When we design a circuit, we just consider the interest frequency band noise, so we don't need select very low fequency.

Toward a circuit design , will give the spec of the frequency band to calculate the noise figure.

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3. ## Re: flicker noise question

It depends on your freuqnency range. Generally we choose 1k or 10kHz as the lowest band edge.
Actually toward low frequency, noise-f curve will be flat instead of go to infinity.
So, flicker noise integration is not infinite.

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