Conditional offset of comparator

[kickoff1111]

Hi all,
I am doing a comparator with conditional offset. It needs the offset should be about 30mV when compared level is about 0V; and offset should be < 5mV when compared level is > 0V and < 2V.
The supply is 5V. I was thinking is there any way to activate an optional input gate or to activate an optional differential load when input level is near 0V. Thus might be able to change offset when input level is near 0V.
But seems no way.
Can anyone help me?
Thanks a lot!

 

[tony_lth]

1. Using one OpAMP open loop to generate a switch signal. You can set the OpAmp Comparator, which is open loop, with threshold, say 1mV. So, when input is 0V, the output is 0V; otherwise, the output is +5V.
2. using this switch signal to control a SPDT switch, switch between +30mV offset and +5mV offset.
Goood luck.

 

[kickoff1111]

Hi Tony,
Thanks for your help.
But there is another issue. Since there is also a constraint that the comparison delay time should be limited within a short period. If we do in this way,
will the comparison delay time be increased a lot?
Thanks for your reply.

---------- Post added at 03:02 ---------- Previous post was at 02:48 ----------

Hi Tony,
Also, what's the best method to create a selectable offset comparator?
I mean how to design it in best way? Trim input gate size or load?
Can you give some suggestions?
Thanks a lot!

 

[tony_lth]

Hi Tony,
Thanks for your help.
But there is another issue. Since there is also a constraint that the comparison delay time should be limited within a short period. If we do in this way,
will the comparison delay time be increased a lot?
Thanks for your reply.

Hi, you can use ADS to simulate and get delay data.