Gregory began his NFL career in 2006 as a rookie free agent out of Syracuse. He has spent his entire 6-year career with the Chargers.
The deal is reported to average $2-3 million per year. He started 13 games last season and has the special teams experience that the Patriots covet.
Gregory made the news in 2010 when he was suspended 4 games for violating the league's policy on performance enhancing substances.