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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