A Chinese state-owned company has prepared a $23 billion bid to buy U.S. memory chip maker Micron Technology Inc., people familiar with the matter said, in what could be the largest foreign takeover by a Chinese firm.

Tsinghua Unigroup Ltd., China’s largest chip design company, is willing to pay $21 a share for Micron, a 19.3% premium over its Monday closing price, one of the people said. Shares of Nasdaq-listed Micron have fallen by nearly half in the past year. They closed at $17.61 on Monday.

A letter outlining Tsinghua’s bid has been presented to Micron, one of the people said.

A Micron spokesman said the Boise, Idaho, company hasn’t received a buyout offer and declined further comment.

Any deal would likely face close scrutiny by U.S. officials in Washington. One question is whether it would be reviewed by the Committee on Foreign Investments in the United States, a panel of representatives from more than a dozen departments and agencies across the U.S. government.