Motorola Inc.: The firm said Monday that...

Motorola Inc.: The firm said Monday that greater demand for its semiconductors has prompted it to move up its expansion plans about six months by hiring 150 more workers during the next nine months.

Motorola hadn’t planned to start bolstering operations until next year, but demand for chips used in wireless communications products, such as cellular telephones, was greater than expected. The new hiring will give the plant a total of 550 employees.

The company also will spend $200 million to upgrade the factory, which it purchased last December from Western Digital Corp.