Hi,
At a guess, if V1 = V2 then I1 = I2 then the current source is balanced and stable. Think of it as a balancing act, or a see-saw, or a rocking boat - up on one side is down on the other. I might be wrong but I play with current sources s frequentlyand the Wilson one isn't as good as might be wished for.
IMHO, assuming the mysterious bubbles are resistors or similar, that is not a truly supply-independent current source, at all, and nor is it temperature-independent, either. Greater Vin = greater I1 & I2 = higher V1 and V2.
If you want to see a super supply-independent currrent source, look for older versions of lm2903, lm339, etc. comparator datasheets for link to app note describing how those devices source is constructed, truly superb thing.
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Hi,
If you are making a reference from a Wilson mirror, good to ponder PTAT and absence of CTAT...
My mobile signal is too weak to upoad the app note I mentioned above. Here's the link:
snoa654A It'll possibly offer to download a pdf, it is from TI, safe...
Document is "AN-74 LM139/LM239/LM339 A Quad of Independently Functioning Comparators", aka snoa654A - May 2004 - Revised April 2013. Current source explanation is bottom of page 4 to midde of page 5.