[SOLVED] help!!-monte-carlo analysis on a comparator's offset

[xuanmulidong]

HI, guys,

Do you know about how to perfom a monte-carlo analysis on a comparator's offset by hspice? I want to get a picture like the one below, it is got from P.E.allen's book.

Thank you for any comment.


https://obrazki.elektroda.pl/46_1258984315.gif

 

[erikl]

Here's a user guide for that:

 

[xuanmulidong]

Here's a user guide for that:

Thanks. But the problem is how to simulate the offset of a latched comparator which needs 2 steps to make a decision? By dc sweep or by transient simulation? If by transient one, how to print an offset voltage?

 

[erikl]

If by transient one, how to print an offset voltage?

In such case I insert an artificial offset voltage (parametrized vdc source) in series with one of the inputs, then run the transient simulations sweeping the offset voltage parameter between the expected values (which you can calculate from values published in your PDK, using mismatch values depending on your W*L values (Pelgrom) and design symmetry). For a first estimation, I'd use ±10mV.

 

[xuanmulidong]

If by transient one, how to print an offset voltage?

In such case I insert an artificial offset voltage (parametrized vdc source) in series with one of the inputs, then run the transient simulations sweeping the offset voltage parameter between the expected values (which you can calculate from values published in your PDK, using mismatch values depending on your W*L values (Pelgrom) and design symmetry). For a first estimation, I'd use ±10mV.

Thanks erikl.

Yes, by trying diferent artificial offset voltage, the minimum offset voltage could be found. But I need a picture like this: https://obrazki.elektroda.pl/46_1258984315.gif. In transient monte-carlo analysis, with big enough differential inputs, the outputs wil be turned over. But how can I catch the points , the offsets, when outputs are turned?

 

[erikl]

In transient monte-carlo analysis, with big enough differential inputs, the outputs wil be turned over. But how can I catch the points , the offsets, when outputs are turned?

By increasing the value of the artificial offset voltage source you could find out when this effect occurs.

But I need a picture like this: https://obrazki.elektroda.pl/46_1258984315.gif.

I don't know if this is possible within ADE tools. You could transfer your MC results into an excel sheet. This is a bit tedious, but it works.

 

[ozgura2]

You can find a good tutorial at the followink link.

https://www.designers-guide.org/Analysis/comparator.pdf

In case to extract statistic parameter define a calculator expression with cross and value functions to determine offset value. Decrease the input speed of signals and apply full speed clock the you do not miss input voltage difference where output changes state.

Erdogan

 

[xuanmulidong]

In transient monte-carlo analysis, with big enough differential inputs, the outputs wil be turned over. But how can I catch the points , the offsets, when outputs are turned?

By increasing the value of the artificial offset voltage source you could find out when this effect occurs.

But I need a picture like this: https://obrazki.elektroda.pl/46_1258984315.gif.

I don't know if this is possible within ADE tools. You could transfer your MC results into an excel sheet. This is a bit tedious, but it works.

offset data can be obtained by .meas command in monte-carlo analysis, and be processed by excel to print the picture I need.
Anyway, erikl, it does work!