* Sees Q1 sales down 15-20 percent sequentially
* Previously expected 15-25 percent decline
* Cites stronger-than-expected China 3G demand
* Shares rise 2.3 percent after hours
NEW YORK, March 2 Programmable chipmaker Altera Corp ALTR.O said on Monday first-quarter sales would decline by a more moderate percentage than it previously expected thanks to demand for next-generation wireless equipment in China.
The company, which competes with Xilinx Inc (XLNX.O) in providing chips to telecommunications and other industries, forecast first-quarter sales to fall 15 percent to 20 percent from the fourth quarter, compared to its previous forecast for a 15 percent to 25 percent decline.
The improved outlook was "largely attributable to better than expected" demand for products for China's 3G wireless networks, Altera said.
Altera, whose customers include Cisco Systems Inc (CSCO.O) and Samsung Electronics Co Ltd (005930.KS), reported in January stronger-than-expected, fourth-quarter profit.
Shares rose 2.3 percent in after-hours trade to $14.89 after closing at $14.56 in the Nasdaq. (Reporting by Ritsuko Ando, editing by Leslie Gevirtz)