An escalating battle between the U.S. and China for supremacy in semiconductor technology is playing out in federal court between Chinese telecommunications giant Huawei Technologies Co. and a Silicon Valley startup backed by Microsoft Corp. and Dell Technologies Inc.

CNEX Labs Inc., based in San Jose, Calif., and its co-founder Yiren “Ronnie” Huang alleged in Texas federal court this week that Huawei and its Futurewei unit have engaged in a multiyear plan to steal CNEX’s technology.

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