The deal, which runs through the 2015 season, is worth $7.235 million per season, with $20.4 million in guarantees, a source told ESPN senior NFL analyst Chris Mortensen.
"Antonio is a special player and person. He is everything we are looking for in a Chargers player," general Manager A.J. Smith said in a statement released by the team. "His talent and contributions to our team speak for themselves. His work ethic and desire to be the best are unmatched. He has been a major part of the success we have had over the past several years, and we are thrilled he will continue to be with us for years to come."
With three other star players unhappy about their contracts, talks with Gates apparently intensified this week. Gates and other veterans are due to report to training camp on Thursday, with the first full-squad practice on Friday.
"I've been blessed my whole career to be with one team." Gates said in a statement released by the team. "It's always good to get [the contract] out of the way. The goal is to win a championship. We all are human and it becomes a distraction even though you might not want it to be. It's always great to be able to go ahead and do what you need to do and get it out of the way."
McNeill, the left tackle who protects quarterback Philip Rivers' blind side, and Jackson, a Pro Bowl wide receiver with two straight 1,000-yard seasons, are unhappy that they haven't been given long-term deals and are expected to hold out through training camp and the season's first 10 games. They are expected to return for the final six games to accrue another season toward unrestricted free agency.
Jackson and McNeill were tendered one-year deals at just more than $3 million each. When they didn't sign the offers by June 15, the Chargers were entitled to offer them their same salaries as 2009, resulting in a loss of about $2.5 million each.
Merriman hasn't signed his tender for $3.269 million, but the outside linebacker was due a 10 percent raise anyway, which would put his 2010 pay at approximately the tender amount. Still, he hasn't said when he'll report.
These negotiations between Gates and the Chargers went much more smoothly than in 2005.
Gates held out during training camp that year, leading general manager A.J. Smith to take the extreme measure of placing him on the roster exempt list in an attempt to break the impasse, automatically triggering a three-game suspension. Gates missed the final two exhibition games and the season opener, which the Chargers lost.
Gates dumped the agent who represented him then and hired Tom Condon.
Since his rookie season, Gates leads tight ends in touchdown catches with 59. He ranks second in yards, 6,223, and third in catches, 479. Gates has led the Chargers in catches each of the last six seasons. In 2009, he topped the Bolts with 79 catches and a career-best 1,157 yards, with eight touchdowns.
The six-time Pro Bowler and a three-time All-Pro was named to the NFL's All-Decade Team (2000-09).
This is the second big contract for a Chargers player in less than a year. Rivers was given a contract extension worth nearly $93 million toward the end of last year's training camp.
The Chargers don't appear close to signing RB Ryan Mathews, the No. 12 overall draft pick and the heir apparent to LaDainian Tomlinson. Mathews missed three practices for rookies and select veterans. ... San Diego coach Norv Turner canceled Thursday's practice. ... Turner said third-year pro Brandyn Dombrowski sits atop the depth chart at left tackle and will get first crack at starting in McNeill's place, with Tra Thomas, 35, providing depth. "That's great news, but it's the beginning of training camp and I'm not taking anything for granted," Dombrowski said Wednesday. "I'm going to take advantage of the reps I get with the first team and try to make the most of this opportunity." Dombrowski was a super-sub last season, making two starts at right guard and seven starts at right tackle in place of injured teammates. While he hasn't played left tackle at any level, Dombrowski said he's more comfortable playing on the left side.
Information from The Associated Press was used in this report.