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vor 9 Jahren

2-2013

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  • Wireless
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  • Mikrowellentechnik
HF-Praxis 2/2013

CCAP The MAX5880 is a

CCAP The MAX5880 is a 128-channel DUC and QAM modulator that drives an RF DAC (Figure 4). It accepts forward-error-correction (FEC) encoded symbols from an FPGA, performs QAM modulation, pulse shaping, and resampling of each QAM channel. It then combines, interpolates, and modulates up to 128 QAM channels to drive an RF DAC. The sample rate for the RF DAC must be more than 2Gsps to synthesize the entire CATV band; it must also satisfy the stringent DOCSIS(r) RF-performance requirements. This design uses the 14-bit 4.6 Gsps MAX5882 RF DAC. The MAX5882 oversamples the 1 GHz band at an update rate of more than 4 Gsps. Note that according to the Nyquist theorem, slightly more than a 2 GHz sample rate is required to synthesize the 1GHz band. However, if a 2.5 Gsps DAC is used, the dominant harmonic distortion products like the NEU_1-8_42x126_HF_2013_Layout 1 2 second Figure 6. Cable RF spectrum of 128 QAM channels using the DUC (MAX5880) and RF DAC (MAX5882) chipset. Temperaturmanagement Industriekomponenten Messtechnik HF-/Mikrowellentechnik Luftfahrtelektronik Entwicklung und Service Link zu: Telemeter Electronic GmbH HF-/Mikrowellentechnik Wir liefern Lösungen ... www.telemeter.info harmonic (HD2) and third harmonic (HD3) can fold back into the 1 GHz cable spectrum due to aliasing (Figure 5A). These distortion products can violate the in-band RF performance requirements for DOCSIS transmitters. However, if a 4 Gsps DAC is used (Figure 5B), the HD2 and HD3 can never fold back into the CATV band. The RF output of the digital RF QAM modulator chipset is shown in Figure 6 for 128 channels that are 6 MHz wide in a 1 GHz span. The RF performance is fully compliant with DOCSIS RF requirements. The DUP and DAC dissipate a total of about 6 W for transmitting 128 QAM channels. That translates to about a 95% savings in power dissipated per QAM channel compared to traditional analog RF modulators. Each of the chips is 17 mm x 17 mm in a 256-ball CSBGA package, thus enabling the RF port density required by downstream CCAP linecards. Summary The new digital RF modulator takes advantage of modern technologies like high-performance wideband digital-to-analog conversion and CMOS technology scaling. The digital RF modulator is a highly integrated solution that also satisfies stringent DOCSIS RF performance requirements. Telecommunications companies now have the opportunity to supply cable service providers with the technology to meet the broadband requirements of tomorrow, cost effectively, today. Maxim Integrated www.maximintegrated.com Links: MAX5880 High- Density Downstream Cable QAM Modulator and Digital Upconverter MAX5882 14-Bit, 4.6 Gsps Cable Downstream Direct RF Synthesis DAC. 44 hf-praxis 2/2013

RF & Wireless Wireless connectBlue Expands its Bluetooth Low Energy Product Suite connectBlue announced the addition of three new Bluetooth low energy solutions to the company's Bluetooth low energy product suite. The new solutions offer Classic Bluetooth and Bluetooth low energy serial communication and consist of the Bluetooth Serial Port Module OBS421, Bluetooth Low Energy Serial Port Module OLS425 and Bluetooth Low Energy Serial Port Module OLS426. The Bluetooth Low Energy Serial Port Modules OLS425, OLS426 and OBS421 are complete Bluetooth low energy OEM modules with UART interface. All three modules have a complete embedded stack and application for replacing serial cables or accessing UART devices using Bluetooth low energy technology with the connectBlue Low Energy Serial Port Service. The single-mode modules OLS425 and OLS426 offer a long battery life while the dual-mode OBS421 module offer compatibility support for both Bluetooth low energy and Classic Bluetooth. The OLS425 has the same small form factor as the OLP425 while the OLS426 offers interchangeability for the connectBlue Classic Bluetooth modules. ■ ConnectBlue www.connectblue.com News myAgilent Personalized Web Portal for Electronic Measurement Agilent Technologies Inc. (NYSE: A) today announced the launch of a new Web portal that allows customers to manage their relationship with Agilent and receive information personalized to their interests and the products they own. The myAgilent Web portal allows customers to: • Register products to receive timely updates, including firmware updates, application notes, service notifications, related forum discussions and more. • Review product warranty and calibration status. • View product order status. • Connect with peers in discussion forums. • Track products of interest and get alerts for special offers. ■ Agilent technologies www.agilent.com Products New 183-219 MHz VCO Crystek's CVCO55FL-0183-0219 VCO operates from 183 MHz to 219 MHz with a control voltage range of 0.5 V ~ 4.5 V. This VCO features a typical phase noise of -123 dBc/Hz@10 kHz offset and has excellent linearity. Output power is typically +8.5 dBm. Engineered and manufactured in the USA, the model CVCO55FL-0183-0219 is packaged in the industry-standard 0.5-in. x 0.5-in. SMD package. Input voltage is 5 V, with a max. current consumption of 25 mA. Pulling and Pushing are minimized to 0.5 MHz and 0.5 MHz/V, respectively. Second harmonic suppression is -20 dBc typical. The CVCO55FL-0183-0219 is ideal for use in applications such as digital radio equipment, fixed wireless access, satellite communications systems, and base stations. ■ Crystek Corporation. www.crystek.com Planar Mixer with high IF bandwidth Spacek Labs Model P1M29B3-2208F is a compact (1.0" x 1.6" x 0.3"), economical and high-performance K-band mixer in the PM Series. With a high IF bandwidth of up to 13 GHz, the full RF/LO range is available in a single unit. This double balanced mixer design performs with a flat-response conversion loss and is optimized for spurious rejection of better than 30 dBc@-10 dBm RF over the band. This versatile mixer design can be ordered either as an active mixer with amplification on any of the ports or as a passive mixer. The active mixer, (shown on the right) has 10 dB of conversion gain and a 3.5 dB max noise figure. Either mixer has a variety of options available such as additional filtering and waveguide or coaxial connectors. These mixers can be incorporated into our receiver system (PR series) or used as stand-alone units. Engineered and manufactured in-house, further customization to the PM series mixers is also available. ■ Spacek Labs, Inc. www.spaceklabs.com 29-31.5 GHz Microstrip Isolator on Carrier 2W9NBP Renaissance has designed a Ka band microstrip isolator that can handle 2 W forward and reverse for satcom applications. With a compact size of 5x6 mm case. It provides low insertion loss in the forward direction and high isolation in the reverse. ■ Renaissance Sales www.rec-usa.com hf-praxis 2/2013 45

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