Shanghai, China-based Spreadtrum Communications said earlier this week that it has completed its acquisition of San Diego-based Quorum Systems. Spreadtrum said in November that it would pay $55M in cash and $15M in stock for Quorum, which designs CMOS radio frequency (RF) transceivers. The deal also calls for up to $6M in cash based on earn-outs over the next two years. Quorum Systems was venture backed by Crescendo Ventures, Greylock Partners, Kleiner Perkins Caufield and Byers, and Enterprise Partners.