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OPA695: noise behavior of the device down to low offset freq?

Part Number: OPA695
Other Parts Discussed in Thread: OPA859, LMH6702


The OPA695 was used in a low phase noise amplifier configuration for a 10MHz / 100MHz system clock distribution circuit.


Studying the datasheet, all noise sources (noise voltage, inverting and non-inverting noise currents) are referenced for

f > 1MHz.  I’m working on a low phase noise distribution system so I’m interested in the 1/f, 1/f^2 noise associated with this part.


Is there any data that may be available that may show the noise behavior of the device down to low offset frequencies (similar to the

attached below but down to 10^0 Hz)?



  • Interesting problem Adam, 

    The CFA OPA695 certainly has an attactive slew rate and BW in a low gain app (I am guessing that for clock distribution). 

    We normally set up our noise extraction down to 100Hz min. That is partially an AC coupled noise preamp limit and spectrum analyzer noise limit.  I could take the OPA695 data and project a curve down following a 1/f profile - it will be quite high looking at the 1kHz number above. I am not aware of any parts that tried to model 1/f^2. 

    If I was setting out to do a low phase jitter clock distribution, might be looking at more modern parts and see if anything might be superior in low 1/f while still providing the pulse fidelity. 

    I could search for a little while for original OPA695 characterization data - but this is going back 24years. 

    There are quite a range of more recent parts that might be more suitable, but not sure without more specs on the clock (edge rates, loading, amplitudes). I was looking at the OPA859, but maybe the slew rate and output are not enough? 

    Of course the LMH6702 is the NSM equivalent to the OPA695, it does show this down to 100Hz, To me, those are very high 100hz noise numbers, but I think all CFA will be about like this,