As cable TV (CATV) companies upgrade their systems to the new DOCSIS 3.0 specifications, low power dissipation has become a major factor. While the downstream path is still the focus of most systems, the upstream needs have increased as more two-way monitor and control functions have been implemented and Voice over Internet Protocol (VoIP) systems have become common. The MAX3518 from Maxim Integrated Products addresses these upstream amplification needs.
The MAX3518 integrated CATV upstream amplifier meets DOCSIS 3.0 requirements. It covers the 5- to 85-MHz upstream band on the cable and can amplify and transmit four quadrature phase-shift keying (QPSK) modulated carriers each at +58 dBmV simultaneously. Both input and output ports are differential, and each requires an external balun. The gain can be varied in 1-dB increments over a 63-dB range by codes received over a standard serial peripheral interface (SPI) three-wire interface.
The amplifier also offers a low 10-dB noise figure and less than 60-dBc harmonic distortion. With a 5-V supply, it consumes 1.25 W when configured for 31-dB gain and +64-dBmV output. The device only consumes 25 mW in the transmit-disable mode. Four power codes are provided to allow maximum supply current to be reduced as determined by distortion requirements.
Housed in a 5- by 5-mm, 20-pin quad flat no-lead (QFN) package, the MAX3518 operates from –40°C to 85°C. Prices start at $5 in 1000-unit quantities. Samples, evaluation kits, and reference designs are available.
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