Ellis, 32, is hitting .167/.310/.167 after seven games this year.
The Dodgers will likely recall Tim Federowicz from Triple-A Las Vegas to share time behind the plate with Drew Butera in Ellis' absence.
True Blue LA's Eric Stephen reports that the cause of the injury is uncertain.
"It is unclear if the injury was caused by normal wear and tear or on a single play. Ellis was thrown out at the plate in the seventh inning on Saturday, and limped ever so slightly walking back to the dugout."
Ellis had a down year in the batter's box last season, hitting just .238/.318/.364 with 10 home runs, but he is known more for his defense and he has made some solid offensive contributions in the recent past. In 2012, he hit .270/.373/.414 in 505 plate appearances. Another performance like that, paired with his solid glove and game-calling aptitude, could make him one of the most valuable catchers in the National League.
He doesn't often receive the same kind of media attention as some of his teammates, but the Dodgers will certainly miss his skill set while he's out.