TDK Corp. agreed to buy InvenSense Inc. in a deal that values the supplier of sensors to Apple Inc. and other smartphone makers at about $1.3 billion.

The offer is worth $13 a share in cash for the San Jose, California-based company, according to a BusinessWire statement on Wednesday. The bid is 20 percent higher than InvenSense’s closing price of $10.84 on Tuesday. InvenSense surged 17 percent Wednesday to $12.72 at 10:22 a.m. in New York.

InvenSense makes gyroscopes, which track motion and rotation in 3D space. In smartphones, they are used to tell if a phone is being held horizontally or vertically, being shaken, or pointing in the direction of a Pokemon, among other uses. TDK, which rose to prominence on cassette tapes in the 1970s, has expanded into batteries, automotive components and now the so-called Internet of Things.

Apple is already TDK’s biggest customer, accounting for more than 11 percent of sales, according to data compiled by Bloomberg. The maker of iPhones accounts for more than half of InvenSense sales.

“We aim to become a strong player in the sensor business with InvenSense as our perfect partner,” TDK Chief Executive Officer Shigenao Ishiguro said in the statement. 

Tokyo-based TDK said it’s funding the deal from existing cash holdings.

InvenSense Chief Executive Officer Behrooz Abdi will receive a $1 million retention bonus if he keeps working for the combined entity through either the anniversary of the execution of the merger agreement or the deal’s completion, whichever comes later, according to a regulatory filing. At that point, one-fifth of his outstanding equity awards will vest early.

Vice President Daniel Goehl will collect a $1 million bonus and receive one quarter of his equity awards ahead of schedule subject to the same conditions. Vice President Mozafar Maghsoudnia will receive a $1.1 million payout and 42 percent of his unvested equity awards.

Abdi can also earn as much as $3.43 million in cash if he remains employed through March 31, 2019, and the company meets certain financial targets in the two preceding fiscal years.

Bank of America Merrill Lynch is acting as TDK’s exclusive financial adviser and Qatalyst Partners is advising InvenSense.