Microwave Engineering Europe - May 2008 - (Page 29)

UWB 29 correct architecture of those blocks is vital to low power consumption. • Complete MAC, conversion layers and security engine. The higher layers of the UWB chip must be able to process several hundred Mbits/second of data in real-time. Only efﬁcient design can ensure these blocks’ low power consumption. • Low leakage power. The UWB chip design must have low leakage power. Unfortunately, because of the amount of elements in the design, and because the elements must run very fast during active mode, this is hard to achieve. However, proper architecture and process selection can help keep this value low. • Power management. Aside from all of a chip’s individual blocks, its power management architecture must be correctly deﬁned to allow transitioning between active and low-power modes. Power-efﬁcient Wireless USB Despite these challenges and the special design techniques they necessitate, UWB (and, consequently, Wireless USB) provides an ideal solution for emerging batteryoperated mobile applications in cases in which low power consumption is critical. Wireless USB has the advantage of speed over other wireless technologies, as it is able to effectively send at 480 Mbits/s over distances up to 3 meters and at 110 Mbits/s up to 10 meters. Even more critical, the UWB protocol has a well deﬁned superframe structure that has speciﬁc time slots. As deﬁned by the WiMedia Alliance, a superframe is 65,536 microseconds and has a period that is divided into 256 media allocation slots (MAS), each one 256 microseconds long. It allows all devices that can hear one another to share a common clock accurate up to a few microseconds even when taking into account drift over multiple superframes, a capability that allows devices to announce when they will be transmitting and when they will be listening. This feature also makes it easy to deduce when the medium will not be in use. This superframe structure allows the UWB protocol to support multiple lowpower modes (apart from the obvious “standby” mode found in other wireless protocols and the “hibernate” mode found in Wireless USB) that can be used during data transmission. In Wireless USB, these modes are labeled “ready,” “standby” and “sleep” and allow both the host and device to sleep in a synchronized way for short periods during data transmission. As a result, the average power consumption of UWB is signiﬁcantly lower than that of other wireless technologies. By its very nature, then, UWB is very low power. This is not because active power (in a cell phone, the power supporting talk time or data transfer) is on, although it is fairly high compared with other standard technologies. Instead, it stems from the fact that UWB works so fast that its total power energy consumption is signiﬁcantly lower than that of a technology such as Bluetooth. Other wireless technologies If today’s power-consumption design challenges can be overcome, the beneﬁts for emerging mobile devices can be signiﬁcant, especially in light of UWB’s power efﬁciency. To fully understand this beneﬁt, consider this true-to-life scenario of a digital still camera with a 4-Gbyte memory card and a dedicated lithium battery providing 3 watt-hours (Wh), used throughout the day as content (such as photos and video) ﬁlls The Skyworks Advantage Extremely high stop-band isolation while maximizing pass-band ﬂatness and minimizing group delay distortion. Programmable in 1 MHz steps. ■ SKY73201-364LF Single Channel Differential I/O SKY73202-364LF Dual Channel Differential I/O O ■ NEW Programmable 1–28 MHz 6th Order Low Pass Butterworth Filters Power Ampliﬁers • Switches • Transceivers • Front End Modules • RF Subsystems Single Package Radios • Mixers • Synthesizers • Switches • Attenuators • Diodes • Technical Ceramics USA: 781-376-3000 • Asia: 886-2-2735 0399 Ext. 990 • Europe: 33 (0)1 41443660 • Email: sales@skyworksinc.com • www.skyworksinc.com Microwave Engineering ● May 2008 ● www.mwee.com http://www.skyworksinc.com http://www.skyworksinc.com http://www.mwee.com

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Microwave Engineering Europe - May 2008 News Contents Comment Cover Feature: How to Succeed as a GaAs Foundry Wireless Networking: Wireless Coverage Where Everybody WINS Wireless Networking: Achieving Good Coexistence in the 2.4 GHz ISM Band GPS and Satellite: GPS developments: Galileo Moves Forward with Successful Giove-B Satellite Launch — Broadcom Targets AGPS in Mobile Phones and Devices Raising the Bar for the Radio: Making 802.11n Work Reducing Power Consumption in Ultrawideband Chips WiMax Catches Second Test Wave Products Calendar

Microwave Engineering Europe - May 2008

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