Agilent Technologies' Santa Rosa-based measurement business bounced back from a slow start on Monday, reporting 5 percent growth in the second quarter.

The division posted $876 million in sales for the period ended April 30, up from $834 million a year ago. Orders grew even faster, up 13 percent from last year.

Agilent, the county's largest high-tech employer with about 1,150 workers in Santa Rosa, is seeing its measurement business accelerate after growing just 1 percent in the first quarter. Smartphones are driving the rebound, said Guy S?? who heads the Santa Rosa business.

"We are clearly seeing an uptick in wireless manufacturing test," he told Wall Street analysts Monday.

Demand is strong in China, where most of the world's cellphones are made. The measurement group's communications test business is up 7 percent from last year, Agilent said.

On Friday, Agilent closed its acquisition of the test division of Centellax, a Santa Rosa company that makes equipment for testing high-speed digital communications systems and components.

Terms of the deal weren't disclosed. About two dozen former Centellax employees will join Agilent in Santa Rosa by the end of July, S??said.

Santa Clara-based Agilent is on track for 2012 revenues between $6.9 and $7 billion, the company said Monday. Agilent hasn't posted $7 billion in yearly sales since 2004.

"Our second-quarter performance demonstrated our ability to deliver strong results despite a challenging economic climate," CEO Bill Sullivan said.

Companywide, Agilent reported income of $255 million, or 72 cents a share, up 28 percent from last year. Quarterly sales were $1.73 billion, an increase of 3 percent.

Agilent's performance beat Wall Street expectations and shares jumped nearly 3 percent in after-hours trading. Shares closed Monday at $38.90 on the New York Stock Exchange, down 55 cents from Friday.