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Wireless Communications Solutions Home Page Mixed-Signal and Analog Products Home Page Key Features of TI's LinEPIC III Mixed-Signal Process TI's Integration Strengths Enable Optimized Solutions for Wireless Systems
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TI's Integration Strengths Enable Optimized Solutions for Wireless SystemsWhen the first digital cellular telephones were introduced in the early 1990s, they contained more than 20 integrated circuits, plus dozens of discrete transistors, resistors, capacitors and other devices. Today, the number of ICs in these systems has been cut in half, with a corresponding decrease in discrete devices. In five years, an ordinary digital cellular or Personal Communications System (PCS) telephone will require only five or six ICs and a handful of discretes. These remarkable changes are due to advances in the underlying process technologies for the manufacture of ICs. New processes make it possible to integrate more functions, and more types of functions, on a single silicon die. As a result, wireless handsets can be made smaller, lighter-weight, more robust in features, and able to function longer between battery charges -- all without an increase in cost. In fact, the cost for manufacturing wireless phones has dropped by 20 percent per year, largely because of savings in component costs made possible by higher levels of integration. Texas Instruments (TI) plays an important role in the wireless industry through its development of advanced manufacturing processes that enable higher levels of integration. TI's TImeline process pointed the way toward the integration of 100-million transistor components. These highly integrated devices can include cores such as the high-speed digital signal processor (DSP) and microcontroller that are at the heart of a digital wireless handset. Recently, TI has announced its LinEPIC* III™ process, which enables the integration of components from the battery management and analog digital baseband sections of the phone. Other processes provide advanced components for the radio frequency (RF) section, and processes in development will enable the integration of additional functions from other sections of the phone. TI's core competencies in advanced digital and mixed-signal processes span all subsystems of digital wireless phones, and the company's process roadmaps promise ever-higher levels of integration in future systems. TI's process strengths enable its wireless customers to develop their systems through customized integration in ways that are most effective for cost and performance. In addition, advanced processes allow the company to offer catalog components that are best suited to the needs of the wireless market. Subsystems of a Digital Wireless Phone For wireless handset manufacturers, the largest single objective of design is keeping the overall cost of the system low. Other important design goals include minimizing power consumption for longer talk and standby times, reducing size and weight to make systems lighter and more mobile, enhancing the perceived quality of the signal through noise reduction and signal modifications, and adding features that differentiate the product. As they integrate components, designers must make tradeoffs among these goals, usually with the overriding consideration that total system costs cannot increase. To understand what challenges system designers and IC vendors face in integrating handset components, it is necessary to understand what the phone's four sections or subsystems do. Specific implementations of each section vary from standard to standard, but their general operation remains the same.
Tradeoffs Involved in Integration At this point in the evolution of wireless handsets, each of the phone's four sections has already become highly integrated. From this point on, manufacturers will be looking more closely at ways to integrate functions from different sections cost-effectively. Generally, integration is most favorable when the functions at issue are similar or have similar requirements, so that they can all benefit from the capabilities of the process. For instance, the battery management section and the voice codec in the analog baseband section both have logic functions along with analog functions. One reason that the LinEPIC III process can integrate these functions well is that it provides both logic and analog transistors. As a different example, the battery management and RF sections both require the capability of handling high voltage. At the battery management end, high-voltage transistors provide system protection against overloads from external battery chargers. The RF section, on the other hand, needs high voltages to produce the power required for transmission. Because of this common requirement, a process with high voltage capability can serve well to unite battery management with certain RF functions. By contrast, some functions are widely dissimilar and make less sense as candidates for integration -- at least for the foreseeable future. For instance, the RF power amplifier requires a large transistor with a thick oxide so that it can produce a large amount of power without burning out. The digital baseband section, on the other hand, requires extremely small, extremely fast transistors for high-speed processing with low power consumption. Not only do these functions require entirely different transistors, but also both types of functions are potentially noisy. If they were integrated, they would need a wide, unused isolation area between them to prevent their interfering with each other, making the chip more expensive because of the unused silicon. All integration decisions are based on factors like these, plus such questions as whether integration increases or decreases the number of package pins and thus component cost. Different designers have different priorities and will choose different methods of integrating and partitioning the functions of their systems. Without several process options being available, it is impossible for a wireless handset manufacturer to evaluate the tradeoffs and achieve the optimum integration for the design. A Range of Process Options TI offers a range of processes for digital and mixed-signal integration, and it continues developing new processes that will make higher levels of integration possible in future. By providing several process options, TI makes it possible for its wireless customers to find the best way to achieve their system design goals. TI works closely with its wireless customers during the development phase of new processes. TI endeavors to understand its customers' design requirements, including their cost curves, so that it can create the right processes for their systems. In addition, TI participates in industry standards bodies to keep current with and, when necessary influence, the evolution of new wireless technology. TI is already working with customers on this next phase of integrated analog baseband/power management ICs to be able to offer them a distinct competitive advantage in the next generation of wireless phones. TI also develops advanced package options that support system-level integration. Among these are the MicroStar™ BGA for near-chip-scale footprint, and the PowerPAD™ thin shrink small outline package (TSSOP) and thin quad flatpack (TQFP) with heat sink for high-frequency performance up to 2 GHz. As the industry moves toward the third generation of wireless technology, integration is becoming more important than ever. Today, functions from different sections of the phone are being combined, so that integration decisions may vary considerably from design to design, depending on standards and design goals. TI is maintaining its leadership in process technologies by offering a range of options that help designers optimize their systems. As a result, TI wireless customers will continue to have the capability of offering smaller, lighter, inexpensive, more feature-rich handsets in the future.
Trademarks:
* EPIC stands for Enhanced Performance Implanted CMOS. LinEPIC is a mixed-signal version of the TI digital CMOS process known as EPIC.
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