Mobile Phone Application Processor

Since 2.5G, mobile phone has gradually been evolved into a multifunctional platform with video, data, entertainment, commerce, and payment functions, instead of providing voice service only.
 
In 3G era, the speed-up of the network operation has proved to be a stimulus to multimedia application. The baseband processor has failed to satisfy the need of the increasing multimedia applications. It would take a tremendous workload and long-term of development if using baseband processor to fulfill such tasks. Thus, multimedia application processor has emerged when mobile phone became fast consumable.
 
To enter into multimedia application processor field is much easier than that of baseband processor. When it comes to baseband processor, many factors must be considered such as years of experience in operating communication protocol stack, power consumption, cost and volume; and the higher patent fees, large amount of manpower and financial input for R&D, for which the medium and small enterprises can hardly afford. However, there are many enterprises armed with video decoding and 3D acceleration technology (basic knowledge needed for the multimedia application processor); and the investment of manpower and financial support is much less. While the market scale of cell phone has reached more than 0.7 billion units, showing a very promising prospect. Currently, the multimedia application processor manufacturers can be divided into 5 categories.

The figure is about the global market scale of multimedia application processor, which is expected to be up to USD 2.8 billion in 2008.

The additional application ranges of future cell phone, not limited to multimedia, consist of Wi-Fi, UWB, A-GPS, bluetooth, ultrared, 3D game, E-payment, security and so forth, and the emergence of such applications gave rise to the application processor. The fact that application processor must cater to the widespread application of cell phones is determined by the volume of the cell phone. The application processor with single function has no future. Early ones usually worked as camera control or signal disposing, and then, music, short film shooting, TV application, etc. At the same time, many low-end applications are integrated into the baseband processor.

Application processor demand includes the following 5 facets:

1  Performance, including multimedia processing and multi-task implementing performance
2  Cost, including chip cost, EMS memory cost and consumption
3  Power consumption, including standby time and operation time consumption
4  Enlargement, performance dynamic allowance, developing-style operating system and supporting JAVA
5  Application development, compatibility between hardware and software, the third party support, designing tools and support, services. 

Application processor can be divided into 3 groups in term of designing, one is array processor with single ARM kernel, another is ARM kernel with DSP, and the last one is gate-level logic circuit design. In addition, there are fewer manufactures applying RISC structure.
 
The greatest merit of ARM kernel is its easily-constructed operation platform and excellent performance, while its demerit is that the ratio of performance to power consumption is inferior to DSP. Consequently, operation unit with ARM kernel fits interlink with up-class software so as to control multi-devices of cell phones easily, while DSP suiting for the operation of fixed model. The performance of ARM has much to do with the operation frequency, so that if you want a more powerful performance, frequency must be improved which in turn leads to increased power consumption. The kernel of TMS320C55x DSP, used in multimedia processor by Texas Instruments, has much higher efficiency than that of ARM11.

HI-BIT DSP takes a long period of development and needs a large amount of manpower and money, for that reason, no medium or small-sized enterprises look to develop HI-BIT DSP alone. Therefore, the array processor with ARM kernel is used in a wide range. Display card makers have gathered plenty of experiences in graphic processing that can design multimedia application processor by gate-level logic circuit.