TAIPEI (Reuters) - Global sales of mobile phones are expected to grow to between 1.1 billion and 1.2 billion units in 2007, up as much as 20 percent from about 1 billion units sold last year, a Texas Instruments (TXN.N: Quote, Profile , Research) official said on Friday. "We are optimistic on the growth momentum of low-price mobile phones," Terry Cheng, the president of Texas Instruments Inc. (TI) Asia, told Reuters on the sidelines of a seminar in Taipei. TI is the world's biggest cellphone chip maker.