ON Semiconductor Corp. has completed its acquisition of a San Jose-based public Wi-Fi tech company. The Phoenix-based semiconductor manufacturer (Nasdaq: ON) had announced in March its intention to buy Quantenna Communications Inc. (Nasdaq: QTNA) for $946 million. ON said on June 19 it completed the acquisition for $24.50 per share in cash. Quantenna's stock ended trading Tuesday at $24.51 a share. ON Semiconductor shares were trading around $19.53 by mid-afternoon Wednesday, down 6 cents....