Texas Instruments Inc. agreed to buy modem maker Amati Communications Corp. for $395 million in cash, the companies said. The deal supplants the one Amati made last month to be acquired by Westell Technologies Inc., which makes systems for phone line connections. Westell will receive a $14.8-million "breakup" fee, TI said. San Jose-based Amati, whose annual sales are about $15 million, has been losing money. With the deal, Dallas-based TI would obtain a technology that allows data to be sent at high speed over existing copper phone lines, which could make Internet access, high-quality video and other services more widely available. Under the deal, equal to $20 a share, TI will start an all-cash tender offer for Amati stock Tuesday. TI shares fell 63 cents to close at $98 on the New York Stock Exchange; Amati shares rose $4.56 to $19.75 on Nasdaq.