Analog Devices, Inc. announced the AD9856, a 200-MHz, CMOS QDUC that provides an integrated, low-cost, low-power, mixed-signal answer to discrete analog implementations. The AD9856 integrates a 12-bit, 200-MHz DDS, a high-performance, high-speed 12-bit DAC, reference clock multiplier circuitry, digital filters, and other DSP functions onto a single chip to form a complete quadrature digital upconverter device.

The AD9856 functions as a universal I/Q modulator/upconverter device in communications applications where cost, size, functional integration, and dynamic performance are critical concerns. The 12-bit DDS architecture contained in the AD9856 also positions the device as a superior and cost-effective single-tone synthesizer and FSK modulator.

The AD9856 accepts a baseband complex 12-bit data word from a digital ASIC, demultiplexes the data into I and Q paths, upsamples the I/Q data, modulates sine and cosine carriers from the DDS, digitally combines the quadrature carriers, and converts the data into an analog carrier, agile over a DC to 80-MHz bandwidth, via a 12-bit DAC.

The AD9856 represents a true breakthrough in IC communications technology for a number of reasons:

It doesn't matter how you decide to integrate which functions in a communications system these days because you will please some people and make others miserable, making demands for a different level or combination of integration. Analog Devices obviously devised this particular combination for at least one customer but, surprisingly, it is a combination that may be acceptable to most of the the different system proponents. This sort of solution is going to proliferate as other manufacturers get to the stage of being able to produce high frequency converters with high resolutions. So it is here with the 12-bit resolution DAC built-in allowing the chip to be mostly digital. The 80-MHz output capability allows the upconverter to work at the majority of the popular IFs.

The most important breakthrough here, to me, is that this can be a standard product for any form of digital modulation allowing its use in an amazing number of applications, and bullet-proofing it for future applications as well. This part and its derivatives will be extremely successful. When considering the price of the part it should be remembered that the DAC itself could have commanded the dollar amount by itself only a year ago.