Mobile phones are acquiring ever-richer features. From a device intended for talking only, new uses have been added: a music and radio player, a navigation device, and an email reader and web browser. All these applications use wireless connectivity: RF technologies designed not for the mobile network, but for mobile phones (wireless mobile connectivity).
Bluetooth earphones and speakerphones are the best-known connectivity technologies. Today, with the aid of Bluetooth technology, people can listen to stereophonic music and transfer multimedia files between their PC and their phone. GPS is also considered connectivity technology. It is used to determine location and for satellite-based navigation, and is expected to be integrated extensively in mobile phones.
In addition, wireless LAN (WLAN) has become more readily available for use in mobile phones both for Internet use and for voice calls, nowadays conducted over free networks (such as Skype) or on converged networks with the mobile network that enables ordinary voice calls integrated with Wireless LAN at reduced rates.
Many mobile phones already include an FM receiver as a standard component. Today, we have already begun to see broadcasting of FM from mobile phones, so that consumers can listen to music stored on their phones and listen to GPS navigation instructions on their car stereo system, see an incoming call and the caller ID on the radio screen (RDS), and use the car speakers as a speakerphone.
Additional technologies include watching mobile TV on a phone screen, and advanced technologies such as ultra-low power (ULP) that connects the mobile phone to sports and medical devices, near field communications (NFC) that enables mobile phones to be used as wireless credit cards, ultrawideband (UWB) that transfers information at very high rates over short ranges, and WiMAX, enabling long-range broad-band connectivity.
Most applications today need connectivity, resulting in a steady rise in the growth rate of connectivity technologies in mobile phones.
(Source: IDC's "Worldwide Mobile Phone Connectivity Chipset 2008-2012 Forecast and Analysis," Doc #210513, p. 26, February 2008)
It is important to note that the mobile phone market exceeds one billion new phones per year so that the growth rate of 10% anticipated for WLAN in 2008 translates into 100 million WLAN components per year.
From Multi Chip to Single Chip
Standards such as Bluetooth and WLAN began as systems with multiple components, generally containing a digital component that performed the MAC and baseband functions, and a separate RF component that contained the transceiver. Sometimes, a power management component was also included that contained the necessary voltage regulators. Subsequently, all the functions required were integrated on a single silicon wafer. In a component such as the BRF6300 (a Bluetooth component), the integration was made possible using TI's DRP™ technology, which enables digital implementation of system parts whose implementation until recently had been analog.
With technological advances, efforts have been focused on integrating several systems onto the same silicon wafer for the purposes of miniaturization and cost reduction. As a result, the connectivity components have been transformed into multiple transceiver components, which, when combined with high frequency digital circuits, creates a variety of mutual interference phenomena. New and innovative mechanisms have therefore been designed in these components to enable simultaneous operation of multiple transceivers, such as those for Bluetooth, FM (RX, TX) and WLAN (802.11 a/b/g/n), while eliminating or minimizing such interference.
Choosing the manufacturing technology
The need to squeeze more and more technologies into the mobile phone, combined with the downward pressure on mobile phone prices, has led to attempts to reduce the silicon surface area. One way to achieve this is by switching to the latest production technology (shorter channel length, such as 65nm). This transition is generally relatively easy for digital circuits, but constitutes a substantial challenge for designers of RF and analog circuits, and sometimes even requires the redesign of such circuits.
Power consumption is a significant (and competitive) factor because these components are powered by the phone's battery (which is shrinking all the time). Much development efforts are concentrated on reducing power consumption, and finding creative solutions to issues such as high leakage current in sub micron CMOS technologies, power-aware firmware, and creating more efficient receivers and transmitters.
One of the ways to reduce the time to market is to reuse intellectual property (IP) blocks. This approach saves hardware, firmware, and software development and integration time because it uses the same version of the firmware/ software for several components concurrently. For example: in TI's WL1273 component, which is a WLAN, Bluetooth and FM component, use is made of the same IP as in the BL6450 component which is a Bluetooth and FM component.
Mass production of mobile connectivity components has led to the need for very high quality components. To this end, solutions have been developed that enable the use of software tuned radio to compensate for the deviation from the tolerances by analog components, as well as a self-test capability that encompasses most of the component's activity, while retaining low manufacturing costs.
The complexity involved in integrating connectivity components is not only at the hardware and RF level, but also at the software and system level. In order for the connectivity component to have synergy with the rest of the components without causing mutual interference, integration of the component is required at the system and software levels.
Many connectivity technologies are penetrating mobile phones. The mobile phone as a platform poses many challenges to connectivity component designers, and hence connectivity components for the mobile phone market are distinctly separate from components with similar functionality that are not intended for use in mobile phones.
About the Authors
Amir Faintuch is business marketing and product management director for Texas Instruments' Mobile Connectivity Solutions Business Unit and Ram Machness is the Ecosystem marketing manager.
DRP is a trademark of Texas Instruments. Bluetooth is a registered trademark of the Bluetooth SIG, Inc. Wi-Fi is a registered trademark of the Wi-Fi Alliance. All registered trademarks and other trademarks belong to their respective owners.
A version of this article ran in the April 2008 issue of Israel's TapeOut.