CHARLOTTE - After a week of minor signings, the Carolina Panthers made their first significant move in free agency on Friday by coming to terms with linebacker Landon Johnson on a three-year deal.

Johnson spent the previous four seasons with the Cincinnati Bengals, starting at all three linebacker positions in the same 4-3 defense the Panthers use. Johnson racked up 112 and 109 tackles in the past two seasons and could unseat Na'il Diggs as a starter at outside linebacker for the Panthers.

Johnson visited Carolina on Thursday and agreed to the deal Friday morning.

"The city, the team and the coaches all made a tremendous impression on him," said Johnson's agent, Andy Simms, who declined to release financial figures of the deal. "It's a tremendous opportunity for him to further his career and get a chance to play where he can help the team."

The Panthers had been quiet in what's been described as a weak pool of players since free agency began a week ago. Carolina signed three players -- guard Keydrick Vincent, defensive lineman Tyler Brayton and cornerback Ricardo Colclough -- but they aren't expected to be immediate impact players.

Johnson could be.

A third-round pick from Purdue, the 6-foot-2, 232-pound athlete has not missed a game in four seasons and started every game during the prior two seasons.

Johnson turns 27 next week and would be the favorite to take over at weakside linebacker for Diggs, 29, who signed a contract extension at the end of last season.

Linebacker looks to be an area of strength for Carolina. Jon Beason became the starter at middle linebacker last season and led the team in tackles. Thomas Davis has improved as the starter at the other outside linebacker spot.

The Panthers still have several holes to fill, notably on the defensive and offensive lines and at safety and receiver.

Johnson is the third defensive starter to leave the Bengals in free agency. Defensive end Justin Smith left for San Francisco, and free safety Madieu Williams signed with Minnesota.