This thread has been locked.
If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.
Part Number: OPA301
Hello.In the data sheet, there is 40uVpp, 0.1-1MHz.I tried to get this number from the Noise density graph, but failed. Attached my calculations, based on you “Lecture Manual”.Data from the data sheet:Input Voltage Noise, f = 0.1Hz to 1MHz 40µVPP
From the Noise density graph: enf=0.3µV/√Hz at 10Hzf0=10 Hzennormal= enf√ f0=0.3*√10=0.95µV/√Hz at 1HzfL=0.1 Hz , fH=1 MHzenflicker= ennormal√(ln(fH/ fL))=0.95*√(ln(1M/ 0.1))= 0.95*√(ln(107))=0.95*√(ln(107))= 0.95*√(4)=3.8 µVrmsenflicker(pp)=6* enflicker=6*3.8=22.8 µVPP
Please advise where is my mistake.
It seems that the 40 uVpp in 0.1-1MHz range comes from this Application Report:
Enflicker = En_white*√Fcn*(ln(fH/fL)) - (1)
where, En_white (white noise) = 3 nV/√Hz from the datasheet
and Fcn is the frequency at which noise is √2 x white noise specification. For 3nV/rtHz white noise, the Fcn then will be 250kHz at √2x3nV/rtHz from the below noise spectral density figure.
If you plug-in the numbers into the Enflicker noise equation, you should get ~6.02 uVrms.
So, Enflicker (pp) = 6*Enflicker(rms) = 6*6.02 = 36.12 uVpp
I think there is some fudge factor or round off associated with making the Enflicker(pp) close to 40 uVpp (0.1-1MHz range) in the OPA301 datasheet.
We are glad that we were able to resolve this issue, and will now proceed to close this thread.
If you have further questions related to this thread, you may click "Ask a related question" below. The newly created question will be automatically linked to this question.
In reply to Rohit Bhat:
Thanks for your answer. It took me some time to learn and understand your answer, and now it's clear.
What it is still not clear:
1. What is the explanation to use the method which I used?( get the Ennormal- the 1/f voltage noise spectral density normalized to 1Hz).
2. Why using this method gives a different result?
In reply to Shlomo Perlshtein:
Thanks again for completing the answer. I suppose that issue is resolved.
All content and materials on this site are provided "as is". TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with regard to these materials, including but not limited to all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement of any third party intellectual property right. TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with respect to these materials. No license, either express or implied, by estoppel or otherwise, is granted by TI. Use of the information on this site may require a license from a third party, or a license from TI.
TI is a global semiconductor design and manufacturing company. Innovate with 100,000+ analog ICs andembedded processors, along with software, tools and the industry’s largest sales/support staff.