Though the judge ruled that there was an infringement he did not order a ban on sales of all Qualcomm chip-carrying phones. The ruling can be appealed to the US courts system.
Broadcom had filed a suit with the US International Trade Commission asking for a ban on all phones with high speed wireless internet connectivity that used Qualcomm chips.
Though Judge Charles Bullock ruled that Qualcomm infringed on some elements of one of Broadcom's patents, it said that two other patents involved in the claim were not infringed.
Both Qualcomm and Broadcom make chips that support the CDMA technology standard which is popular in the US but not in Europe. Qualcomm has separate outstanding law suits against Broadcom.
The Trade Commission is a federal agency and it will make a full review of Bullock's judgment in February. That review can be appealed to a full Federal Court.
Qualcomm has previously been involved in other patent disputes, with Broadcom and others. In 2005 the company accused Nokia of patent infringement. Qualcomm said that the Finnish firm had used methods infringing 12 patents belonging to Qualcomm or its subsidiary SnapTrack.
That case emerged a week after Nokia, Broadcom and other companies complained to the European Commission about Qualcomm and its use of patents for 3G phone technology.
Nokia, Panasonic, Broadcom, NEC, Texas Instruments and Ericsson claimed to the Commission that Qualcomm violated Europe's antitrust regulations
In the recently judged US case Broadcom had originally complained about five patents, but two of those complaints were referred straight to a San Diego court.