[time-nuts] time-nuts Digest, Vol 91, Issue 168

gary lists at lazygranch.com
Wed Feb 29 03:16:15 UTC 2012

That is a good part, but generally for higher frequency circuita, the 
BF862 is used.
> http://www.nxp.com/documents/data_sheet/BF862.pdf

Note the lower capacitance. Noise is higher, but you can parallel the 
devices. They are quite cheap since it is a common part.

You will note LTC plops them in a lot of app notes. Sometimes as 
bootstraps in TIAs, other times to pull extra current out of the op amp 
output to linearize it.

Usually you can get a strip of the on ebay for pocket change, but I 
don't see any there at the moment.

On 2/28/2012 3:06 PM, Bill Fuqua wrote:
> At what frequency do you have 1 nv per square root Hz with opamp and
> what opamp ?
> The 1/f region is the killer and if it is a low frequency shift in the
> input
> effectively changing the threshold then you have to be concerned about the
> 1/f region.
> Discrete embedded JFETs have the best 1/f of all such as the IF3601.
> Go to www.interfet.com
> 73
> Bill wa4lav

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