LeonQQ wrote on Mar 31st, 2009, 7:22pm:Hi all, Suppose I have a one-pole simple amp with the pole at 10kHz, my signal is at 1kHz. To calculate the input integrated noise, I integrated the noise density upto 10kHz, but what should be the low limit of the integration? The lower it is the more flicker noise contribution will be. How low the integration limit is proper? I am confused.
Your inputs will be greatly appreciated.
Leon
Hi there,
This topic has been threshed out several times in the past on this very forum and in great detail. Please search the past posts and you will find more discussion. Incidentally, you will run into a problem if you are going to use the pole frequency as the upper limit for noise calculation, since this will account for only some of the white noise.
For the lower end, I would say that this should in some way depend on the memory of your system. All systems are lossy and will "forget" information collected in the past. Also remember that 1/f noise power per decade is fixed. So going from 10 Hz to 1 Hz will add as much noise as going from 1 billion years to 10 billion years. It may be sufficient to ignore 1/f noise at very low frequencies if it does not add much to your total noise number.
Regards,
Vivek