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| Oscilloscope 100x Pre-Amp for noise measurement? |
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| RogerThat:
I'm looking at this: https://www.analog.com/media/en/technical-documentation/data-sheets/AD8011.pdf 2000v/us slew rate, should be good? Input noise is specified at 2 nV/√Hz.....so that would be for 100mhz: 2 nV / 10000 = (alot lower than 1uV). While writing this it feels odd that noise goes down when frequency goes up. Am I doing it wrong? |
| Karel:
--- Quote from: RogerThat on December 01, 2018, 10:37:19 am ---I'm looking at this: https://www.analog.com/media/en/technical-documentation/data-sheets/AD8011.pdf 2000v/us slew rate, should be good? Input noise is specified at 2 nV/√Hz.....so that would be for 100mhz: 2 nV / 10000 = (alot lower than 1uV). While writing this it feels odd that noise goes down when frequency goes up. Am I doing it wrong? --- End quote --- Yes. In this case, it's 2nV * √Hz. (20uV @ 100MHz) |
| iMo:
@RogerThat: you have to be more clear on what performance you are for. You indicate you want to measure the "noise of the 5V voltage regulator". Why are you looking for a high BW then? People usually are measuring the noise of such stuff in 0.01-10Hz, or 1Hz-10kHz BWs. Why do you want to mess with ~MHz then? |
| dzseki:
Also when dealing with noise measurement, mind the resistor noise, like having a super-duper low noise preamp chip with a 100kOhm feedback resistor kills all the efforts (with having 40nV/sqrt(Hz) self noise). En(resistor)=sqrt(4kTRB) k - Boltzman's constant (1.38E-23) T - Temperature in (K) R - Resistance (Ohm) B - Bandwidth (Hz) |
| Marco:
--- Quote from: RogerThat on December 01, 2018, 10:37:19 am ---I'm looking at this: https://www.analog.com/media/en/technical-documentation/data-sheets/AD8011.pdf --- End quote --- Why though? Why not go straight for something like OPA847? |
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