DC Convergence in DC Sweep of 6t SRAM cell. [Help needed]

Hi,

I am running a DC sweep on a 6t SRAM cell by doing a DC sweep at BL and observing BLbar.

Q - output of inverter near BL
Qbar - output of inverter near BLBar

When I give a rising sweep at BL (BLbar falling) at BLbar reaching a particular threshold (defined by me) I see how much BL has risen upto and also how much Q has risen upto using the .measure statement.

I get DC convergence warnings but then the simulation is finally successful. Now I have the values of BL and Q with me for a particular BLBar threshold defined by me.

To check if the simulation is correct , I just take out the LHS half cell ( the Left hand side inverter and access) and then plug in the DC Bias conditions. (BL value obtained above, vdd, and vg of inverter which is the threshold I had defined earlier) and do a .op analysis.

I expect the value of Q to again land close to the value from the 6t cell simulation but I observe an offset. Not sure why?

I am not sure how DC convergence is affecting the results of the .measure statement. Can someone please give me a lead as to wha might be the problem?

Thanks a lot for your help..