I'm using AD630 (JN grade) as a +1/-1 gain amplifier to take advantage of the precise gain. However with an input of 8.06VDC (low impedance source) I'm getting output values of 8.20 and -7.48VDC in the two gain states.
I'm using AD630 connections as for the lower device in AN308 (http://www.analog.com/static/imported-files/application_notes/AN-308.pdf)
Supply voltage is +/-15 VDC. Supply voltage is clean.
I've checked all the connections carefully but I can't find the source of the gain error. Any advice greatly appreicated.