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Mixers, demodulators suit 4G base stations

Posted: 24 Sep 2009 ?? ?Print Version ?Bookmark and Share

Keywords:4G? RFIC? demodulator? base station?

ADRF 660x, ADRF 670

Analog Devices Inc. has begun sampling the first devices in a range of highly integrated RFICs for 4G cellular base stations.

Dubbed the ADRF 660x and ADRF 670 series, the mixers and demodulators, respectively, are targeted at base station cards capable of both Long Term Evolution and other 4G functionalities.

The cards combine multiple discrete functional blocks into a single device, while meeting the demanding performance required by higher-capacity base stations.

"While the level of integration achieved here is outstanding, we have in no way sacrificed performance, and early indications are base station manufacturers are able to achieve a 60 percent reduction in board space and significant savings on the bill of materials," said Philip Halford, product manager at ADI.

The challenge in designing devices for base stations is to ensure the LO signal is maintained throughout and remains pure, added Halford.

The devices are based on ADI's PLL/voltage-controlled oscillator (VCO) synthesizer, mixer and modulator technologies, which are said to offer excellent phase noise performance, power consumption and linearity for smaller form factor and higher density macro, micro, and picocell base stations.

ADI is also making available evaluation boards for the 670x.

Halford said ADI has delivered samples to, and is in talks with major cellular infrastructure providers, as well as some doing microwave radios, but would not identify the companies. "Now we are aiming to make the ranges available to a broader customer base."

The ADRF660x and ADRF670x series each debut with four pin-compatible devices that cover the commonly used cellular 2G, 3G and LTE frequency bands.

The four ADRF670x mixers integrate a high dynamic range analogue I/Q modulator, RF output switch and PLL with integrated VCO in one compact RFIC. The modulator input bandwidth of 500 MHz is capable of supporting either a specified band or complex IF up-conversion transmit signal paths. In addition, the modulator output supports a linear high output power level for wideband multi-carrier LTE applications.

Meanwhile the range of modulators integrate a high-linearity active RF mixer; RF input balun for single- ended 50 input; and a PLL synthesizer with integrated VCO in one compact RF circuit. The active mixer provides a voltage conversion gain of 6dB, alleviating the need for additional IF amplification over competing passive mixers.

The differential IF output is capable of supporting highest IF frequencies up to 500MHz. The ADRF660x series can be used for receiver path down-conversion and transmit path observation receiver applications.

ADI is also readying a range of dual LVDS I/F transmit DACs, dubbed the 9122 series, that are said to support extremely high LVDS interface capabilities and DAC data rates.

- John Walko
EE Times Europe

For application notes on RFICs click here.

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