Broadcom, seeking to build a powerhouse that leads the market for chips that let electronic devices operate wirelessly, is prepared to launch a proxy battle should Qualcomm spurn the $70-a-share proposal outlined Monday, a person with knowledge of the matter said. Qualcomm is assessing the cash-and-stock proposal, but it's inclined to reject Broadcom's terms. Broadcom would then forge ahead with a direct appeal to Qualcomm shareholders, said the person, who asked to remain anonymous discussing private matters.