Operational amplifier overloaded

[denver56]

Hi! I am having trouble with a commercial filtering board made with operational amplifiers; here a part of the documentation:
"Due to the low cut-off frequency, the baseline restorer takes some time to stabilize after switching on the amplifier or after replacing the MEA. One to two minutes are quite normal. During this time, the filter amplifier input will be overloaded and you will see only a straight line with very low noise. This is considered a normal behaviour and should not trouble you"
DO you know what does it mean "input overloaded"?
Thank you

 

[Tunelabguy]

It means the inputs are different enough that the output is saturated at one extreme or the other. A baseline restorer is essentially an AC-coupled stage that subtracts off the DC offset in the input signal. Depending on the filtering time used to determine that offset it may take a long time before the DC offset is accurately determined, especially after some change in the input that changes that DC offset. So during the time before the filtered DC offset can catch up to the actual DC offset the output of the op amp will be all the way high or low (depending on which way the DC offset is off).