Do you mean that M4 should make a Vds of Q7/Q9? If it is not so how can I make sure to mirror the same current through Q8/Q10?
And if so how can I achieve that? I do not see how to relate Vds of Q7 and Q9 to Vds of M4
Sorry for my late reply
Here you go
For M3 branch and Q8/10 branch say that the biasing current in M3 is 1/4 I8 or I10
then I3 = constant (w3/L) (VGS3-VTH)2
I8= constant (W8/L)(VGS8 - VTH)2
if you are going to desing it such that equal W/L for M3 and Q8/10 then
the VGS8= 2 (VGS3 -VTH)+VTH
Same method you will try if for example IM4 = 0.1 I8/10
Knowing that
VB3 = VGS8 +VDS7 = VGS3 + VDS4
So if VGS8 not equal VGS3
Than VDS7 not equal VDS4
On the other side
if you want to desing such that euqal voltages Then
I3 = constant (w3/L) (VGS3-VTH)2
I8= constant (W8/L)(VGS8 - VTH)2
Say again I want I3 = 0.25 I8
and make VGS 3 = VGS 8 (and so VDS7 will be equal to VDS4)
then
I3 = constant W3/L
I8= constant W8/L
4*W3/L = W8/L
(NOTE: L length should be the same for matching in the current mirror and you will have constraints to try to make the number of multiplers/fingers of W/L an even number for matching))
So then Voltages are the same but different W/L sizes