OPINION RF FRONT-END COMPONENTS
to continue pushing performance and cost frontiers; and recognizing that complete front-end solutions require advanced filtering technology.
While there will be variations within the vast global RF market, in many cases the best way forward is to combine the merits of GaAs and silicon. A good example of this strategy is our multi-mode, multi-band power amplifier module (MMPA): This combines high-performance GaAs PAs with a CMOS controller and silicon-on-insulator (SOI) switches. MMPAs provide a highly integrated approach for today’s increasingly complex RF design, and they equip designers with more room on the circuit board while minimizing engineering time and resources. MMPAs can support more frequency bands than discrete architectures, while trimming board space by 20 percent. What’s more, these multi-band amplifiers feature a versatile design, allowing manufacturers to adopt a common platform for releasing new products at a faster pace, while keeping a lid on design and manufacturing costs.
This includes the promise of a single chip that integrates the RF front-end with the transceiver. The allure of an entity that incorporates the transceiver, PA, antenna switch and filters is hard to deny, but CMOS struggles to maintain efficiency at higher powers. This means that an-all silicon chip may only appeal to designers who are willing to sacrifice performance in favor of CMOS integration.
Now that III-V suppliers are starting to face a potential threat from silicon, how will they respond? By continuing to do what they’ve always done: To deliver what their customers need. Handset designers are focused on optimizing the overall performance, size and cost of their front-ends across their broad product lines, and they don’t concern themselves with the specific technologies used.
For III–V suppliers, the key to success is delivering a complete RF solution, which in many cases is an integrated module, not an individual die; utilizing the best technology for each application; leveraging both III-V and silicon technologies
More than 90 percent of new smartphones and cellular phones use GaAs power amplifiers (PAs) to deliver longer battery life, although CMOS PAs are beginning to make inroads in entry-level applications
Delving deeper To select the best parts in these modules, one must evaluate the relative merits of GaAs and silicon technologies on a component-by-component basis. When it comes to PAs, GaAs continues to outperform silicon designs significantly in terms of current drain and die size. Due to this, GaAs will continue to be widely used for mid-range and high-performance applications, with silicon PAs targeting lower-end sockets where performance is not as important. Nonetheless, silicon will still have a home within even high-performance, GaAs-based MMPA modules. For example, silicon controllers and distribution switches can enhance MMPAs. Additionally, silicon is used for DC-DC converters and envelope trackers that further optimize battery current drain to improve the overall performance of both GaAs- and silicon-based RF architectures.
GaAs power amplifiers (PAs) deliver superior efficiency, providing longer battery life for mobile devices — at about a third the size of comparable CMOS PA die
For years, designers leveraged another GaAs-based technology for its efficiency advantages in RF switches: pHEMTs. Now that steady progress in SOI switches provides comparable performance, this alternative is more widely used in mobile device designs. GaAs pHEMT switches will be reserved for
June 2013
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