SMARTi 3G's in-depth report: Single-chip six-band CMOS RF transceiver enhances your understanding of UMTS (Part 2)
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This article will explain the design ideas of SMARTi 3G and discuss how to use SMARTi 3G to achieve the complex and challenging full-band support functions required by operators, such as adaptive receive baseband filters, fully integrated transmit and receive fractional phase-locked loops, and programmable and controllable front-end outputs. First CMOS UMTS transceiver SMARTi 3G is the first CMOS UMTS RF transceiver from Infineon . The first product of the SMARTi family was launched in 1998. The products were based on the Bipolar Complementary Metal Oxide Semiconductor (BiCMOS) process and were available until 2003. Since then, CMOS C11 RF has become the standard process for all Infineon SMARTi product families. CMOS is now gradually being used in EDGE and UMTS products: CMOS-based GSM/EDGE transceivers were launched in 2004, and the W-CDMA CMOS transceiver SAMRTi 3G was launched in June 2005. CMOS has a cost advantage over traditional RF technologies such as BiCMOS and SiGE because it requires fewer masks and processing steps. Cost and integration are undoubtedly the main factors driving the next generation of RF designs towards CMOS. Market research company iSupply believes that RF CMOS technology will continue to develop and will have about 40% market share by 2009. CMOS is also used in many other products, and the same technology process and product line will truly improve economies of scale. In addition, CMOS is also used in digital baseband, which makes it possible to integrate digital, RF and mixed signal parts on the same wafer, thus creating smaller and more integrated chips. UMTS: a global standard, used in different frequency bands Japan is the first country in the world to launch the UMTS system to mobile users. The first commercial UMTS network operated by NTT DoCoMo was put into use in 2001. While UMTS in Europe is still in the 3G recommendation stage, after four years of market operation in Japan, UMTS has become a mature technology. Many Japanese mobile phone manufacturers are looking for new markets and are very interested in entering the European market. Looking back at the 2G era, there were two parallel development projects, one for the domestic market and one for the international market. This will not happen in the 3G era: the standard is globally unified, with only differences in frequency bands. UMTS frequencies have been specifically allocated in Europe, Asia and Japan for 3G without conflict with other services. In North America, the situation is different: the UMTS frequencies identified by the ITU are already used for 2G applications (1900MHz band) and satellite communications. Despite efforts to free up spectrum resources, UMTS in North America will need to share spectrum resources with 2G applications in the near term. This presents an additional challenge for RF designers, which SMARTi 3G successfully addresses with the use of notch filters (activated in "hybrid filter mode"). The additional 2.7MHz notch filter can be activated via software programming to meet the requirements of UMTS bands II and III. Currently, SMARTi 3G provides a unique opportunity for mobile phone manufacturers targeting the global market. The transceiver supports all six UMTS frequency bands determined by the ITU while addressing the special conditions of the North American market. It allows mobile phone manufacturers to save development time and resources, and one product can be used anywhere in the world. SMARTi 3G supports all 6 frequency bands and can be configured as low, medium and high bands as shown in the following table: The IC's operating frequency band can be set through a 3-wire bus, with six frequency band selections and front-end control outputs, and separate settings for the transmit and receive channels. SMARTi 3G enables designers to develop a variety of solutions, from high-end tri-band solutions to single-band solutions, using the same basic RF wireless design. Typical tri-band applications can be seen in Figure 5: SMARTi 3G typical tri-band application example The typical PCB size of a tri-band UMTS solution using SMARTi 3G is only 370 mm2, with only 74 peripheral components, including matching components, LAN and power amplifier components. Multi-band and multi-mode operation increases the complexity of the front-end, which requires effective control of external components such as LNA, PA and switches. Therefore, SMARTi 3G has built-in flexible software programmable front-end control, which meets the above requirements by switching the state of six dedicated output lines (RXBAND1..3 and TXBAND1..3). Improved versions will add three additional programmable GPOs (general purpose output devices). The basic front-end control function will provide three output states for each band that can be programmed arbitrarily. With this function, different front-end components can be selected. This function can also be extended to special processing of the RXBAND output signal. When the transmission channel is closed, the TXBAND output can be additionally programmed to "low", and when the transmission channel is opened, it returns to the original setting. Typical LNA modules today have different gain level settings to provide a better input power dynamic range. Since the LNA high and low gain mode switching points depend on the receive gain scheme used, RXBAND2 and RXBAND3 can be independently programmed here to achieve the corresponding receive gain scheme. Multi-mode application SMARTi 3G can be used as a front-end control center in a multi-mode environment (e.g. working with the GSM/EDGE radio transceiver SMART PM). This approach allows effective control of current consumption. It is achieved by activating a special mode that switches off the transmit and receive channels and directly controls TXBAND1..2 and RXBAND1..2. in conclusion After UMTS became the global standard, the demand for high-performance transceivers with high speed, small size and low power consumption has risen again. SMARTi 3G provides mobile phone manufacturers with the solution they desire. Supporting all six UMTS frequency bands, excellent technical features and a compact size of 5mmX5mm, SMARTi 3G enables mobile phone manufacturers to design a globally common system through a simple platform, thus saving development time and resources and bringing products to market faster. SMARTi 3G will attract more and more attention from mobile phone manufacturers and platform providers. The economical, practical and highly innovative SMARTi 3G is expected to occupy a high market share and continue the glory of the SMARTi family. By Irina Prjadeha, Dr. Rainer Koller, Infineon Technologies Glossary
BB BasebandBiCMOS
Bipolar Complementary Metal Oxide SemiconductorCMOS
Complementary Metal Oxide SemiconductorDAC Digital to Analog
ConverterDigRF Digital Radio FrequencyEDGE Enhanced Data Rate for GSM EvolutionEVM Error Vector MagnitudeFDD Frequency Division MultiplexingHSDPA High Speed Downlink Packet AccessIIP2 Second Order Intercept PointICSS Initial Cell Search SpeedupITU International Telecommunication UnionLNA Low Noise AmplifierOPV Operational AmplifierPLL Phase-Locked LoopRF Radio FrequencyRX ReceiverSiGe Silicon GermaniumSNR Signal-to-Noise RatioTFRC Transmission Format and Resource CombinationTRX TransceiverTX TransmitterUMTS Universal Mobile Telecommunications SystemVCO Voltage Controlled OscillatorW -CDMA Wideband Code Division Multiple AccessWFSGA Very Fine Pitch Hemispheric Grid Array
References [1]W. Thomann et al., "A Single-Chip 75-GHz/0.35-μm SiGe BiCMOS W-CDMA Homodyne Transceiver for UMTS Mobiles," IEEE Proc. RFIC 2004, Fort Worth, USA, pp. 69-72 , June 2004.
[2] DigRF: The Digital Interface Standard; retrieved from http://www.digrf.com/
[3]3GPP TS 25.306: “UE Radio Access Capabilities”
[4] “CMOS use rises in mobile handsets, says iSuppli” (2005) retrieved from http://www.eet.com/news/latest/showArticle.jhtml? articleID=170701228
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