psn-l-digest-request@.............. wrote:

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>| Message 1                                                           |
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>Subject: Op amp front end noise
>From:    John Popelish 
>Date:    Wed, 09 Mar 2005 20:57:24 -0500
>
>I am getting pretty deeply into the design process for a velocity coil
>seismometer amplifier and filter and have decided to try ot quantify
>the relative noise performance of various candidate opamps versus coil
>resistance.  Here is the list of low noise and general purpose types
>(which I have on hand) that I am comparing:
>
>AD706
>AD708
>AD820
>AD822
>ICL6750S
>LF411
>LMC6062
>LMC6462
>LMC6482
>LT1007
>LI1115
>LT1124
>LT1128
>LT1677
>LT1047
>LTC1051
>LTC1151
>MAX400
>MAX410
>MAX420
>MAX427
>MAX430
>MCP6022
>OP07
>OP177
>OP2604
>OP27
>OP97
>
>Do you have any suggestions for other candidates I might evaluate?
>
>My biggest difficulty in completing this task has been resolving the
>wide variation in noise specifications for the various types to
>produce a valid comparison in the DC to 10 Hz frequency range,
>especially comparing the chopper types to the others.
>
>  
>
You might try the OP80A, which is very low noise and has a high input 
impedance.  A decent second could be the LF356, unless you're locked 
into another package.  Just a thought.  Of course, the OP80 is out of 
production now, I believe, but if you can find some, let me know!  
Seriously...

Doug Gavilanes
Garden Grove, CA.
gavilan1@.............



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