[RunningDroid]

This image from the OpenStreetMap Wiki seems to be the best match for the type of mini roundabout you're talking about:

https://upload.wikimedia.org/wikipedia/commons/7/77/Mini-rou...

It seems like most of the examples on the mini roundabout page‡ are larger mini roundabouts for some reason though

‡: https://wiki.openstreetmap.org/wiki/Tag:highway%3Dmini_round...

[masfuerte]

Yes, and they can be smaller. The circle is about the right size but it has lots of room around it. Imagine a crossroads at the meeting of two residential streets, both just wide enough for two cars. Stick the circle from your picture in the middle of that imagined junction. That's what the mini roundabouts are like on the 1930s suburban estate I live next to.