This is a classic switched-gain "3 opamp" diffamp. It actually has 5 gain ranges, from 1 to 256.
ftp://jjlarkin.lmi.net/Diffamp_osc.JPG
This is for an ADC with fs ranges from +-10 mV to +-40 volts.
The board is very tight (16 channels of attenuators, pgas, filters, adc's, test relays) so I kept the parts count down. I did the math and figured it would be stable. What I didn't count on was that it has two oscillation modes, differential (stable) and common-mode (unstable!) In common-mode, both opamp outputs scream in phase at about 500 KHz so the voltage divider string doesn't divide, it just tosses in phase shift, working into the capacitances of the DG408s. It oscillates hardest on the highest-gain (10 mV) range, doesn't oscillate at unity gain.
I could scale down the resistor string, but all those 0.05% resistors are calculated and purchased and in place. It's easier to just kluge in the caps for now.
The INA154 ref runs at +2.5 volts so the signal can go into one of those horrible single-supply pseudo-differential ADCs.
John