Offset testbench in autozero amplifier

[EmbdASIC]

I have an amplifier with some 5mV offset, for which im using the autozeroed compensation scheme. The problem is, in the uncompensated testbench, i can easily estimate using follower configuration with montecarlo sims. HOWEVER, once the autozero compensation is in place, how will the testbench then look like?? what nodes would our montecarlo sims look for ? How should the amplifier testbench look ?

Best Regards,
EA

 

[leo_o2]

Check feedback node with montecarlo for offset.

 

[EmbdASIC]

Thanks for your reply.

But notice that im of course already checking the node voltage. The autozero technique has switches to cancel the effective offset at input or output. One needs to know how to setup the testbench to get correct offset from monte carlo sims !

I want to know: the reduction in my offset through my montecarlo simulation testbench once autozero is applied
If someone can post helpful tips, please do!

Regards,

 

[leo_o2]

Firstly, find the offset without auto-zero with Montecarlo. Then, add the offset and auto-zero to check if the offset will be cancelled by auto-zero.

 

[EmbdASIC]

Thanks for your reply.

But what you have mentioned is something i already know, and did before posting on the forum. I've already written that my montecarlo sim without autozero has 5mV of offset. Now i am needing the correct estimation method with autozero.

https://obrazki.elektroda.pl/88_1298546918.jpg

If anyone has better idea on how to monitor offset in montecarlo ONCE AUTOZERO is in place, please suggest something useful.

Thanks all,

 

[erikl]

Not sure, but I think this should be feasible by PSS analysis (+ MC), see e.g. this paper. You could probably find more info in this forum.

 

[haykding]

Why you can't sim it again using follower configuration , and view output node ? What is the problem with nulling amp ?

but ... you can do tran sim, one node drive with for ex. vdd/2 dc source, and second one node sweep from 0 to vdd , and measure offset in the output ... in ideal case , comparator will switch when ramp signal and static signal get crossed .. but you will see another picture...

 

[EmbdASIC]

Thanks Erikl,

I usually try edaboard first, due to the better response here. Let me give this method a look..

Regards,
EA