Trying to use the AD8606 in BGA package on a fully symmetrical layout, the two amps on the chip do not show identical behaviour. Configuration used is non-inverting amp w 2V ref and 200x amplification. A3B3C3 works as expected, whereas A1B1C1 always oscillates in low-kHz range. Supply is 5V.
As mentioned, the circuit is the same for both channels and the layout symmetric. I can not figure out where the problem might be, as we had been using the AD8605 and AD8608 in different configurations before, but have to switch to BGA for space constraints.
What can i do to track down the problem?