thanx barry, your suggestions lead me on the right track ..exactly what i wanted to know.. just one more question..i totally understood the ckt you explained before .. but i have a ready circuit (which obviously is not working and made me post this thread) .
In this ckt the i/p signal is been given to the TLV2372 ckt (the one who made it expected i/p to be in the range ±8V though) and then o/p is given to the voltage divider circuit for offseting it to 1.65V and from there to the ADC.
And i still coudn't figure what is the gain of TLV2372. i went over the datasheet but its all Latin to me. proceeding with your circuit is the smartest thing for me to do now. but was just curious to know what was wrong with this ckt.