Stevie Johnson signs with Chargers

Free-agent wide receiver Stevie Johnson agreed to a three-year contract with the San Diego Chargers on Tuesday.

Johnson had visited the Chargers and Patriots since his release from the 49ers last week. In San Diego, he will help to replace receiver Eddie Royal, who left the Chargers this offseason to sign a free-agent contract with the Bears.

Johnson said he is excited to be able to catch passes from quarterback Philip Rivers.

"He is one of the quarterbacks I always wanted to play with," Johnson said Tuesday, according to the team's website. "I'm happy to be here and happy to work with him ... My strength is just getting open. I'm going to be open for [Philip]. I'm a security blanket."

The 49ers released Johnson, 28, after just one season with the team.

Johnson, who had a contract cash value of $6.025 million for the 2015 season, according to ESPN Stats & Information, caught 35 passes for 435 yards and three touchdowns on 50 targets in 13 games for the 49ers, the seven-year veteran's lowest output since his second season.

The arrival of free-agent wideout Torrey Smith made Johnson, acquired last year for a fourth-round draft pick from the Bills, expendable in San Francisco.

He had three straight seasons of at least 1,000 yards receiving in Buffalo from 2010 to 2012.

ESPN.com 49ers reporter Paul Gutierrez contributed to this report.