An anonymous $15bn acquisition offer for FPGA chip vendor Xilinx has reportedly been submitted this week, with Qualcomm and Broadcom/Avago the most likely contenders. Qualcomm has been working closely with Xilinx in the past year on its first server system-on-chip, with the smaller firm providing the FPGAs (field programmable gate arrays) to power accelerators and other elements. This has seen Qualcomm moving closer to Intel’s infrastructure heartland, and since Intel acquired Xilinx’s primary FPGA competitor, Altera, last year, the logic of a Qualcomm/Xilinx merger seems strong. Avago, which has acquired Broadcom and taken its name, would have a less urgent need for an FPGA vendor, except that it has been acquiring technologies in many areas, with an overall goal of…