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A few months ago, I wrote about PortalPlayer audio codecs in MP3 players (see Tear Down: PortalPlayer media processor drives the Samsung YH-820MC MP3 player). One of the potential competitors I identified that could encroach on PortalPlayer's return to the mobile market was Texas Instrument's OMPA2 platform.
As a follow-on to those statements, I decided to investigate handsets that have already implemented the OMAP2 platform, looking at the handsets' functionality and its associated components, while diving deeper into the OMAP2 itself. The handset I identified for my investigation is the Sharp SH902i, which operates on the EGSM 900/1800/1900 frequencies (Fig. 1).
This 3G handset is used primarily in Japan has a unique display. Measuring 2.4 in., the QVGA (240 by 320 pixels) screen incorporates an advanced super view (AVS), which is useful for ensuring privacy. When viewed from the side, the screen can't be read. Such a feature is desired by the millions of people sending text messages (According to a recent release at Mylasia's thestar.com, over one trillion text messages were sent in 2005).
The SH902i is built with dual camera modules. The outer camera has an effective resolution of 3.16 Mpixels using a CCD element with autofocus, while the inner CMOS imager has a resolution of 110,000 pixels. The outer camera contains motion-picture stabilization, which works with all image sizes and shooting modes for indoor, outdoor, and nighttime conditions (up to a max bit rate of 750 kbits/s). Up to 1 Gbyte of audio content can be stored in its miniSD Memory Card, allowing users to create their own music library. The external dimensions of the handset are 4.2 by 2.0 by 0.91 in. It weighs in at 4.55 oz.
1. The Sharp SH902i 3G handset is based on TI's OMAP2 processor platform.
In all, there are six key devices that enable to functionality in the handset (Table 1).
TI's OMAP2 platform is interesting from an applications capabilities point of view. As has been mentioned previously (OMAP antes up for handsets), the OMAP2 has four engines to control functionality. They are an ARM1136 (as opposed to the ARM936 in the previous generation); a C5x DSP; a 2D/3D graphics processor; and an imaging/video accelerator. Each engine can be turned off independently to minimize power consumption (Fig. 2).
2. In addition to the OMAP2 processor, the handset is built with dual cameras.
While most designers are aware of these facts, they may not know that the OMAP2 can include system-in-package memory stacking. In this instance, Sharp has integrated the Elpida Mobile SDRAM.
Given the capabilities of the OMAP2, I was surprised to find other chips that provide duplicate functionality in the handset. For example, the imaging accelerator is capable of driving a 3-Mpixel camera. However, Sharp chose to employ its own camera processor. Also, the integrated DSP is often used for MP3 and sound playback, and yet there's an NEC melody audio LSI and an Asahi Kasei audio codec.
Semiconductor Insights recently analyzed the digital standard-cell area on TI's OMAP2 Applications Processor platform with the company's gate-density and standard-cell analysis tool. Comparing the standard-cell libraries used to design ICs, manufacturers can determine the level of sophistication of the cell library, to better benchmark their devices across different technology types and the fabs that are used. The difference between this analysis and others is that it provides an exact count of the number of gates used, not an estimate, providing the most accurate results.
For the OMAP2 platform, three types of cells fill the area analyzed: functional/logic cells; cells used to provide the power supply; and dummy cells filling unused space. There were 243 unique functional cells found among a total number of over 115,000 functional cells (Table 2).
Three types of cells were used to provide the power supply to the standard cell region: power switches, decoupling capacitors, and sensors. Cells used as a filler of empty space contained only a poly/diffusion layer with poly in the shape of either simple bars or invertors, or capacitors. The final utilization result is 72.6%, if the power switch cells are excluded, or 74.0%, if the power switch cells are included into the area occupied by the functional cells.
To put this into perspective, it's estimated that an equivalent device will require about 150,000 gates to meet the functionality and size requirements of a 4G system. While the OMAP2 platform is about half of the way there, with 4G expected to reach main stream markets in 2010, this should be an achievable goal.
About the author
Gregory A. Quirk is a technology analyst for Semiconductor Insights. He can be reached at gregoryq@semiconductor.com.
This article is excerpted from Semiconductor Insights' Handset Design Win (HDW) subscription service.
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