Clearwire has secured an additional $920 million in debt financing, bringing its total fundraising efforts to $2.8 billion in debt and equity. The latest cash infusion brings the mobile WiMAX provider well past its previously stated funding goal between $2 billion and $2.3 billion, which it needs to build out its 4G network.

“With this latest tranche of additional funding, we have not only exceeded the amount of capital that we have previously stated we needed to fully fund our business plan, but we have also secured additional capital that will allow us to expand more aggressively by covering more people, and with more capacity than we had previously planned,” said Bill Morrow, CEO of Clearwire, in a statement.

Clearwire recently raised $1.564 billion from existing investors, including Sprint Nextel, Comcast and Intel. The company then raised more money, some of which was used to pay off existing debt of $1.4 billion. That fundraising round brought Clearwire’s net funding efforts to just under $2 billion.

Today’s announcement brings Clearwire’s total endowment to $2.8 billion. The money was raised by Clearwire Escrow Corporation, a subsidiary of Clearwire’s mobile WiMAX division. The notes will be issued in a private offering exempt from SEC registration requirements. The sale of the new notes is slated for Dec. 9.

Clearwire plans to use the proceeds to speed its aggressive network buildout, which aims to cover as many as 120 million people with mobile WiMAX in 80 markets by the end of 2010.

The company still has the option to raise an additional $295 million through a stock offering to its public shareholders.