(Adds the European Commission and Synopsys declining to comment, in paragraphs 5-6)

By Foo Yun Chee

BRUSSELS, Dec 23 (Reuters) - U.S. chip design software company Synopsys is set to win conditional EU antitrust approval for its $35 billion buy of Ansys , people with direct knowledge of the matter said on Monday.

The biggest technology sector deal since Broadcom's $69 billion purchase of software maker VMware a year ago, it also marks the first Big Tech merger under new EU antitrust chief Teresa Ribera.

To address EU competition concerns, Synopsys this month offered to sell its optical design tool maker Optical Solutions Group as well as Ansys PowerArtist, other sources have told Reuters.

The company is expected to offer the same remedies to the UK competition watchdog after it voiced concerns about the impact of the deal on innovation and prices last week, the people said.

The European Commission, which acts as the antitrust enforcer in the 27-country European Union, is scheduled to end its preliminary review of the deal on Jan. 10. It declined to comment.

Synopsys also declined to comment and reiterated its statement to the UK Competition and Markets Authority last week where it pointed to its proposal to sell its Optical Solutions business.

Companies are looking to Ribera, who took up her post this month, to see if she will continue her predecessor Margrethe Vestager's tough line on Big Tech deals.

Ansys' software is used in creating products ranging from airplanes to tennis rackets for players such as Novak Djokovic.

Ansys PowerArtist is a tool used to analyse and reduce power use to enable power-efficient design.

(Reporting by Foo Yun Chee; editing by Alison Williams and Jason Neely)

((foo.yunchee@thomsonreuters.com; +32 2 585 2866; Reuters Messaging: foo.yunchee.thomsonreuters.com@reuters.net))