Shares of Nvidia Corp jumped more than 11 percent on Wednesday, as investors bet on strong sales for the company's chips used in mobile devices like smartphones and tablets.

The chipmaker forecast strong 2013 sales, but analysts said the outlook was too optimistic given the current macro environment and increased competition as rivals Intel and Advanced Micro Devices Inc step on the gas.

We find it difficult to believe that, in the current economic environment, a company that is 80 percent exposed to consumer spending has meaningful visibility into demand over the next 18 months, analyst Daniel Berenhaum at MKM Partners said.

Nvidia said it expects its Tegra product, which is used in mobile devices like smartphones and accounts for about 10 percent to total revenue, to contribute roughly $1 billion to sales in fiscal 2013 -- much higher than analysts' expectations.

In an interview with Forbes on Tuesday, CEO Jen-Hsun Huang said he expects Android tablets running Nvidia's new quad-core processor to be available this year, ahead of competitor Qualcomm Inc.

Nvidia, which also competes with Samsung Electronics Co and Texas Instruments, said it has 70 percent of the Android tablet market share. This accounts for about 30 percent of the overall tablet market, which is dominated by Apple Inc.

A dreary economy had weakened sentiments for chipmakers on supply chain concerns caused by Japan's earthquake in March and lower PC sales.

For 2013, Nvidia expects revenue of $4.7-$5.0 billion, higher than analysts' expectations of $4.45 billion.

Shares of the Santa Clara, California-based company rose to $14.64 in heavy trading on Wednesday.

They have fallen a third since May 27, after a former Nvidia financial analyst pleaded guilty to a criminal charge in the U.S. probe of insider trading at expert networking firms and hedge funds.

(Reporting by Rachana Khanzode in Bangalore; Editing by Joyjeet Das and Sayantani Ghosh)