fonts with equal weight and perfect circles

Question

I am attempting to find a font that meets this criteria:

I need it to be geometrical (the circles in the lowercase "d" to be a perfect circle)
I want the fonts to be single weight throughout. As in the where the shoulder of the lower case "d" meeting the stem, it does not narrow. Same with the lowercase "n". These are just example letters.

Should look like Helvetica, or Avenir. Avenir has a perfect circles but the "n" narrows out.

Here is an example I found of a non-narrowing weight. It should stay equal throughout. As in the "same thickness."

There should be a ready-made font. How do I search about such criteria? Can I avoid using Illustrator correct the narrowing?

example of round and no narrowing