offset value measurement of sense amplifier in cadence spectre

[parminder]

Dear all,

i want to evaluate the offset value of my sense amplifier . i have given vin+ = 900mv (dc) and vin- = 870 mv to 930 mv (ramp) . now how to measure the offset . can any one please help??

 

[KlausST]

Hi,

what about a schematic?

Klaus

 

[parminder]

thank you for the response @KlausST . please find the schematic for reference

can anyone please respond ??

 

[dick_freebird]

First, get your output to single ended using an A=1 vcvs.
Then, get your input stimulus set up so it's also differential
driven (@ legit input ommon mode) from a single ended
primary source.

You can then feed that node through a feedback network
from output to input that puts the amp in its "happy place"
for a DC result, or sweep it and use calculator cross()
function (with some somewhat elaborate args, which you
would have the fun of building up). Personally I like a
clean DC test loop with a gain block and attenuators, old
school (but needful of accommodating the fully differentlal
style).

 

[Dominik Przyborowski]

As this is clocked comparator, the best seems to use vccs sensing differential output and integrating it into capacitor connected to negative input (while positive input is on dc potential). Integrating capacitor should have initial conditions set to dc level on positive input and PSS should be used as analysis.
At steady state, on negative input you should see triangle waveform oscillating around positive input DC minus offset.

vccs gm and capacitor value can be choose based on supply level and clock frequency.