problem with the instumentation amp

[malik_123]

i am using to amplify a 1mv signal with the analog instrumentation amplifier
Ad 620

with + 12v/ -12 v power supply , gain resistance i used was
10 Ω
it worked very good for one day , i get very good result but after two days , whenever i On the circuit , it gives the sine way for some time of the desired amplitude
but after the some time its gain decreases and also the wave form gets clipped on both the sides

i replaced the power supply , but the behavior of the cck did not changed

can any one tell me what is going on , and what could be the problem

 

[FvM]

Has your circuit any means to guarantee input common mode voltage within allowed range, e.g. bias resistors?

 

[malik_123]

i figured out that problem was
GROUND RETURNS FOR INPUT BIAS CURRENTS
i consulted the datasheed and then
i just connected the two resistor from inverting and non inverting inputs to the ground . because of which the gain of the instrumentation amplifier was decreasing after some time