The actual offset value in this application is somewhat irrelevant. Temperature stability of the offset voltage and bias current is. The 10811 met it's specs with the LM208 so there is no need to get a substantially better part even though as you pointed out it is easy. My point was not to use anything worse like what was suggested by the op. Didier On Wed, Sep 11, 2019, 3:48 PM Charles Steinmetz <csteinmetz@yandex.com> wrote: > Didier wrote: > > > The LM208 is a single op-amp with low offset (<3mV) and low bias current. > > Even 3mV offset is verging on horrible for a "precision" opamp these > days -- it's hard to find any respectable opamp that doesn't do lots > better. > > The secret sauce of the LMx08 series is the super-beta input pair, which > matches FET opamps for input current but also holds that low (room-temp) > input current over the full temperature range (the input current of FET > opamps generally rises by at least 10x to more than 1000x at warmer to > hot temperatures). > > There is no need for extraordinary measures -- there are a number of > more modern opamps specifically designed to upgrade LMx08 sockets. The > OP77 is one: > > < > http://pdf.datasheetcatalog.com/datasheet/analogdevices/206654345OP77_c.pdf > > > > The LT1012 and OP97 are two more. I've used both extensively, and > finally settled on the OP97 for this sort of application: > > < > http://pdf.datasheetcatalog.com/datasheet/analogdevices/140679914OP97_d.pdf > > > > Best regards, > > Charles > > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. >