clearwire logoClearwire is raising a lot more cash as it attempts to build a national high-speed, 4G wireless network using WiMax technology. Today, it announced $920 million in debt financing.

The company already raised a little less than $2 billion from strategic investors and the sale of bonds, so its recent new funding now totals $2.8 billion. Clearwire says it has the option to raise another $295 million from public shareholders.

The company was born last year from a partnership between Sprint and the previous company called Clearwire, with investment from Google, Intel, Comcast, Time Warner, and others. It has ambitious plans to reach 120 million people with its network by the end of next year, with early coverage in Silicon Valley.