norton method on current mode dac

[yefj]

Hello,I have a R2R shown bellow i want to see the output by norton method.
i tried to test 0100 word.But as you can see i dont have a two port system.
How to do norton with such a system?
Thanks.

 

[sutapanaki]

You don't need Norton transformation here. Just try to do it with current division starting from the left side.

 

[yefj]

Hello,I see the current from B0 is Vref/2R but how i get to the current going to B2 with current divider?
There is R between the 2R ,how i handle this case?
Thanks.

 

[sutapanaki]

Yes, current into the MSB switch is Vref/2R. But to the right of BO you see also 2R, so the same current will go to the right, Vref/2R. To the right of B1 you see again 2R and thus the current entering B1, which is Vref/2R will split in two. The current into the MSB-1 switch is 0.5*(Vref/2R) and the same current goes to the right of B1. Continue like this to the end.

 

[yefj]

Hello,You say that in B0 we have I/2R and B1 current is I/2R , how we get a split in current?
Thanks.

Yes, current into the MSB switch is Vref/2R. But to the right of BO you see also 2R, so the same current will go to the right, Vref/2R. To the right of B1 you see again 2R and thus the current entering B1, which is Vref/2R will split in two. The current into the MSB-1 switch is 0.5*(Vref/2R) and the same current goes to the right of B1. Continue like this to the end.

--- Updated Oct 7, 2020 ---

Yes i think i got the idea.
Thanks.

 

[sutapanaki]

Yes, you've got the idea