The 31 year old has been out of contract since leaving Sporting CP by mutual consent in August, have spent much of last season on loan with Malaga.
The defender, who made just two La Liga appearances last term, has also played for AC Milan, FC Twente and Standard Liege, while he turned out eleven times for Newcastle United during the 2006/07 campaign.
Internationally, he has sixty-eight caps for the United States and will be looking to compete for a place in next summer’s World Cup squad having made just one competitive appearance this calendar year.
He joined a QPR side who sit second in the Championship, two points behind Burnley, who they face on Saturday afternoon.
Harry Redknapp’s men, who have played a game less the leaders, are favourites at 6/5 to win the division.