Electronic hardware and software design company

Mentor Graphics

(MENT)

said on Tuesday that it plans to offer $150 million of convertible subordinated notes to help fund its acquisition of

Innoveda

(INOV) - Get Report

.

Mentor said the purchasers would have the option of an additional $22.4 million of the notes for a 30-day period after the sale.

The company has offered to purchase Innoveda for $3.95 a share in cash.

Shares of Mentor fell as low as $15.59 in after-hours trading Tuesday after closing at $17.20 in the regular session.