Dec 30 (Reuters) - Chip company Advanced Micro Devices Inc"s (AMD.O) $35 billion all-stock deal for peer Xilinx (XLNX.O) is now expected to close in the first quarter of 2022, delayed from a previous target of end-2021, the companies said on Thursday. "While we had previously expected that we would secure all approvals by the end of 2021, we have not yet completed the process," the companies said in a statement. Shares of AMD were marginally up in trading after the bell, while those of Xilinx fell 3.6%. AMD announced the deal in October, intensifying its battle with chief rival Intel Corp (INTC.O) in the data center chip market. Amid U.S.-China tensions, chip deals face approval challenges from Chinese regulators, who are known for their lengthy and sometimes opaque antitrust reviews. "Our conversations with regulators continue to progress productively, and we expect to secure all required approvals,” the companies said. Chip designing peer Nvidia Corp (NVDA.O) has been struggling with getting regulatory approval for its deal for UK-based chip firm ARM Ltd, with the U.S. Federal Trade Commission earlier this month suing to block the deal over competition concerns. read more