Post simulation mismatch for the Gm/C filter

[elonjia]

I designed a Gm/C filter, and for the pre-simulation using a schematic, it works well, but after I finish the layout (passing DRC and LVS), I find my circuit does not work well! Looks like there is a leakage path and my output is going down from the post-simulation result, what's the possible problem for this? Thanks!

 

[jjx]

Didn't you do any extraction of parasitics? And if so, those are the reason for your degradation. That's what happens.

Can you explain what you mean with "leakage path" and what "my output is going down" means?