Investors seek more ways to buy into smartphones, tablets

— -- Apple's rapid surge to become the most valuable U.S. company has focused attention on the explosive growth in smartphones and tablets — and sent investors searching for other ways to cash in on the mobile computing boom.

Unlike personal computers, where technology investing used to be simple with a few leaders such as Microsoft and Intel, mobile computing has many players whose shares trade on U.S. markets.

They range from Apple to lesser-known companies such as Qualcomm, ARM Holdings, Texas Instruments and InvenSense. Many are components suppliers that are behind the scenes, making them harder to identify than the companies that actually sell the gadgets.

"You have many different companies making (parts) that go into tablets and smartphones," says Brian Colello at Morningstar.

The components, and their makers, include:

•Application processor. The brain of a smartphone or tablet is the computer chip that runs the basic functions and apps. It's a hotly contested area. Apple designs the chips that go into its devices, and it competes primarily with Qualcomm, which has top share of chips for smartphones, Colello says.

Other key players include Nvidia and Texas Instruments (TI), says Gary Mobley of Benchmark Capital. Nearly all phones and tablets, including Apple's, use chips that adhere to a design from ARM Holdings.

•Connectivity and cellular chips. These allow mobile devices to link with wireless networks. Intel and Qualcomm are top makers of chips that allow devices to connect with cellular networks, while Broadcom is a leader in making chips that allow phones to connect with Wi-Fi networks, Mobley says.

Marvell and TI are also key players, he says, while TriQuint and Skyworks make chips that boost wireless signals.

•Glass and touch and motion sensors. Corning is a leading maker of the glass, with nearly 90% of the market, says F. Drake Johnstone of investment adviser Davenport. OmniVision's imaging sensors are often found in devices with cameras, says Andrew Rassweiler of IHS iSuppli. Broadcom makes a line of motion chips, used in many mobile devices, including Apple's, Mobley says. TI makes a variety of chips that serve this function in some mobile devices, he says. A smaller company, InvenSense, makes gyroscope chips that alert a mobile device to movement, Rassweiler says.

It's far too soon to declare victors. Intel, for instance, aims to break into the mobile market, Morningstar's Colello says. "It's much more fragmented (than the PC business)," he says.