Microwave Engineering Europe - December 2007 - (Page 29) 3G PHONE TEARDOWN 29 changing depending on the position of the phone. In fact, a common accelerometer part from ST powers both designs, now using a similar multichip package to the Wi-Fi device described earlier. The LIS302 contains two analog chips to sense “which way is up” and drive display reorientation: a sealed MEMs chip for the three-axis accelerometer proper, and an analog processor used for interface to the digital world in which it communicates as a system peripheral. As can be seen in the device callouts, the N95 makes significant use of localized supply regulation. Step-down dc/dc converters from National take care of business near the RF power section, the latter implemented with multichip packages combining GaAs amplifiers with CMOS power controllers and antenna switches for keeping external complexity in check. Smaller-scale regulators are also used elsewhere, and LED drivers from TI and National join up for lighting management. Despite some dispersed regulation and conversion, dedicated analog ASICs for power management run the big show, with the N95 employing a mix of custom devices made by ST and a dedicated merchant market chip from TI (TWL92230) used for powering the N95’s applications processor. All in all, this collection of analog components can be thanked for orchestrating miserly power consumption and delivering workable talk and standby times in the face of a rich product feature set and sub-4-Whr battery. Much of the system audio is believed to reside within one of the ST custom analog power parts (4396299), which also employs a second, simple, in-package silicon chip for implementing area-consuming passives to keep the die size of the more-complex core device as small as possible. Separate audio amplifiers from Texas Instruments round out the analog audio chain; both are small in size but large in impact, considering the import of quality audio in the consumer experience. Other specialty analog chips – such as Hall-effect sensors (for detecting product articulation in the dual-slider N95 design) and an Analog Devices piezo motor driver (for controlling motion in the N95’s autofocus camera lens – are also found, joining a bucket of other quietly contributing mixed-signal parts too numerous to describe in this brief article. All those details and a few omissions aside, the message is quite simple: Once you look past the low-power processors and dense memory chips of the N95, analog rules. n About the author David Carey is president of Portelligent, an Austin, Texas, company that produces teardown reports and related industry research on wireless, mobile and personal electronics (www.teardown.com). This article was reprinted courtesy of EE Times Europe. MICROWAVE ENGINEERING EUROPE Free subscription at: www.mwee.com/subscribe MWEE newsletter at: www.mwee.com/newsletter Microwave Engineering ● December 2007 ● www.mwee.com 028_029_MWEE.indd 29 22/11/07 17:12:24 http://www.teardown.com http://www.mwee.com/subscribe http://www.mwee.com/newsletter http://www.mwee.com
For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.