my multisim simulation does not work in real world

[SampathBandara]

I change the op amp because my 1 st op amp has some phase shift (according to my knowledge some time I am wrong). But my new problem is I have DC off set (my project need almost all zero DC offset)

Furthermore, when I use RC high pass filter still I have DC offset

If you have any suggestions please tell me

Important- I put RC filter each op amp output but it is not working for me and I have not yet construct this circuit in real world. I hope it should work

Note

Yellow line- out put

Red line is –In put

Figure-1,2 without RC filter

Figure-3,4 with RC filter

[SampathBandara]

My other images

[johnsold]

You definitely need the series capacitors to eliminate the DC offsets. 

Any high pass filter will introduce some phase shift. The question becomes how much phase shift is acceptable?  The high pass filter will have the most phase shift (in angle units) at the lowest frequency. Once you decide on the maximum acceptable phase shift, you can then determine the size of the capacitors required to produce that.

Lynn

[SampathBandara]

Thank you for your  reply

you mean final op amp output or each op amp output

[johnsold]

It depends on how much DC you can tolerate at the intermediate stages. For the AD8000 the input offset is typically 1 mV and 10 mV maximum.  With each stage set for a gain of 10 the output of the second stage could be at 1 V if both of the first two stages had worst case offsets.

I would play it safe and use a capacitor between each stage. If you do that, you will have 3 cascaded filters. That means that if one filter  has 10 degrees of phase shift at a specific frequency, then you will have a total of 30 degrees of phase shift at that frequency for the entire circuit.

Lynn