By design, AdSense tracks every access to every AdSense-enabled web sites for billing and payment purposes. Essentially, an AdSense-enabled web site gives its web log to Google in real-time.
That means every time you visit a site with a "Ads by Gooogle" sign, you will leave a digital footprint on Google's system (even if you don't click their ads). Google can definitely track you by using the IP address. It may also use cookie to track you.
In essence, each AdSense-enabled web site is host that monitors activities on the Internet for Google.
AdSense is not just an advertising platform; it's also a "spying" platform for average people who don't know the implications.