The addition of Carter could be linked to the playing status of starting rookie cornerback Devin McCourty, who is listed as questionable for Sunday's game against the Green Bay Packers because of a rib injury.
The Broncos signed Carter as a rookie free agent out of Florida State in 2009. He spent the first 14 weeks of last season on Denver's practice squad before going on the active roster for the final three games. Carter played in two games as a rookie, with one start, and finished with one solo tackle and fumble recovery.
Jackson was signed by the Patriots on Dec. 10 as a free agent. The 5-foot-11, 193-pound defensive back originally was selected in the third round of the 2008 NFL Draft by the Atlanta Falcons out of LSU.
Jackson played in 31 games for the Falcons, starting three and compiling 51 tackles, one sack and one interception. He returned his first career interception 95 yards for a touchdown against the New Orleans Saints on Nov. 9, 2008. He also recorded an interception in an NFC wild-card playoff game against the Arizona Cardinals on Jan. 3, 2009.