AD620 drift


I use ad620 for my load cell conditioning circuit. It amplifies load cell signal to +/- 10V range. I need to improve drift cause by temperature. When I apply just a little hot air to my pcb and output changes.

I have ad620 with a gain of 660. I have +10V and -10V regulated from +/-15V. I use reference pin of ad620 in order to remove dead weight. because after ad620 I further amplify my signal with a gain of 12. then a low pass filter. My filter is around 3Hz.

I use 10ppm thin film resistor on gain adjustment and 25ppm in my filter and voltage regulator circuits.

does any one has an idea on getting better temperature performance.