(Reuters) - Chipmaker Intersil Corp will reduce its workforce by 11 percent to cut costs and revamp its product portfolio.

The company expects to incur charges of about $9 million in the second quarter due to the restructuring, it said in a regulatory filing on Wednesday.

Intersil employed 1,643 workers as of December 31, 2011.

The company said the restructuring plan includes trimming operating costs by about $40 million annually.

Intersil's revenue has declined for the last four quarters. Costs, however, have not fallen, hitting its operating margins.

The company posted a wider-than-expected loss for the first quarter, as operating margins shrank to a negative 1.4 percent from 10.5 percent the year ago.

The company earlier this month had expressed its intention to limit its focus to a few top markets and segments during presentations to analysts and investors.

Shares of the company closed at $10.52 on Wednesday on the Nasdaq.

(Reporting by Himank Sharma in Bangalore; Editing by Sriraj Kalluvila)