OPA192: OPA192 output noise density

jinan an

Part Number: OPA192
Other Parts Discussed in Thread: THS3491, OPA211, LMH6629, OPA1611

Hi, Gentleman:

I evaluate the OPA192 and want to check the OPA192 output noise.

For the 0.1Hz to 10Hz noise, I must develop one own band pass filter to measure the noise?

for the 10Hz to 10kHz, I must use a spectrum analyzer? The spectrum minimum input frequency is only 9KHz, how you measure the output noise spectrum between 10Hz to 10KHz?

I check your precision lab training, but didn't find the answer what I need. Would you give a little more detail explanation?

Thanks for your support!

over 3 years ago

0 Michael Steffes over 3 years ago

Guru 47485 points

MOrning Jinan,

I am actually stepping through these measurements in a series of AudioXpress articles (this next one is the noise preamp for 10Hz to 100MHz) - if you can get those (subscription only, so I cannot link them in) it will answer your questions. The one I am finishing right now is converting the measured output noise to input referred plots (the OPA192 is easy, only voltage and resistor noise terms, a CFA like the THS3491 is more involved). An earlier one showed an updated (improved) 0.1Hz to 10Hz time domain preamp design.

0 Raymond Zhang1 over 3 years ago in reply to Michael Steffes

TI__Mastermind 47796 points

Hi Jinan,

In addition to Michael's suggestion, I found the following application note on the topic. Hope this helps.

https://www.ti.com/tool/TIPD147?keyMatch=SPECTRUM%20ANALYZER%20NOISE&tisearch=Search-EN-everything

https://www.ti.com/lit/ug/tidu016/tidu016.pdf?ts=1596123577152&ref_url=https%253A%252F%252Fwww.ti.com%252Ftool%252FTIPD147%253FkeyMatch%253DSPECTRUM%2BANALYZER%2BNOISE%2526tisearch%253DSearch-EN-everything

If you need further assistant, please let us know.

Best,

Raymond

0 Michael Steffes over 3 years ago in reply to Raymond Zhang1

Guru 47485 points

I looked at those documents Raymond, this OPA211 one is a gain of 100V/V which will be 800kHz rolloff for the 80MHz OPA211, its 1/f is pretty low. For flat noise postamp, probably no higher than 200kHz. We normally go doubly terminated 50ohm out to 50ohm spectrum analyzer like the HP3589 (10Hz to 150Mhz I think). the articles are describing a LMH6629 composite structure with the OPA1611.

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OPA192: OPA192 output noise density