It looks like a better candidate would be the LTC2054, which has a typical bias current of 1 pA at 25C and is essentially constant up to 45C.
Randy On Thu, Apr 27, 2017 at 5:02 PM, Randy Evans <randyevans2...@gmail.com> wrote: > Charles, > > You are absolutely correct. I misread the data sheet. It's interesting > that all three LTC1050s behave exactly the same. They have the same lot > code number.but I would expect more variation. Live an learn. > > Randy > > On Thu, Apr 27, 2017 at 12:18 PM, Charles Steinmetz <csteinm...@yandex.com > > wrote: > >> Randy wrote: >> >> but I recently noticed the meter reads -0.08 when the >>> input is open on the 1V range and the null switch is on 0.0001 >>> This equates to a -8uV reading. >>> I believe this is due to the input bias current of the LTC1050 >>> * * * >>> However, this would imply an 8pA bias current, >>> which is much higher than expected. >>> >> >> I am attaching the relevant portion of the LTC1050 datasheet. Note that >> at 25C, the 1050 has an input offset current spec of +/- 20pA (both typical >> -- max is ~5x worse). I would expect a total input offset of +/- 20uV >> (typical) in your circuit. (The 0.5uV typical input offset voltage is not >> a significant contributor in this context.) >> >> Best regards >> >> Charles >> >> >> >> _______________________________________________ >> volt-nuts mailing list -- volt-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/m >> ailman/listinfo/volt-nuts >> and follow the instructions there. >> > > _______________________________________________ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.