June 17 (Reuters) - Apple AAPL.O has convinced a U.S. appeals court to throw out a $300 million verdict by a jury that found it infringed wireless standard-essential patents owned by IP management company Optis Wireless Technology.

The U.S. Court of Appeals for the Federal Circuit on Monday sent Optis' case back to Texas for a new trial after determining that the jury instructions in the previous trial were flawed.

The decision marks the second time that a nine-figure U.S. patent verdict for Optis has been overturned in the case.

An Optis spokesperson said on Tuesday that the company remains "highly confident the Court will establish fair compensation for the critical Optis patents that enable high-speed connectivity for millions of Apple devices."

An attorney and spokespeople for Apple did not immediately respond on Tuesday to a request for comment on the Federal Circuit ruling.

Plano, Texas-based Optis and its affiliates sued Apple in 2019 in Marshall, Texas federal court, arguing that the tech giant's iPhones and other products violated their patent rights in technology related to the LTE wireless standard.

A jury found in 2020 that Apple owed $506 million for infringing Optis' patents. U.S. District Judge Rodney Gilstrap ordered a new trial on damages in 2021 after finding the award may not have been in line with Optis' responsibility to license the standard-essential patents on fair and reasonable terms.

A new jury awarded Optis $300 million in damages after the retrial later that year.

The Federal Circuit on Monday overturned the award and remanded the case for a new trial on both infringement and damages. A three-judge panel said Gilstrap improperly worded the jury verdict form by combining all of the patents at issue into a single infringement question.

"The problem with the district court's single infringement question is that it deprived Apple of its right to a unanimous verdict on each legal claim against it," the appeals court said.

A UK court separately ruled last month that Apple owes Optis $502 million for infringing Optis' UK wireless patents. Apple has said that it plans to appeal the ruling.

The case is Optis Cellular Technology LLC v. Apple Inc, U.S. Court of Appeals for the Federal Circuit, No. 22-1925.