ADI unveils two high-speed converters for wireless applications

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ADI's AD9779

Norwood, Mass. — Today Analog Devices, Inc. (ADI) trumpeted the first 16-bit digital-to-analog converter (D/A converter) to achieve a sample rate of 1 Gsamples/s, and a 14-bit analog-to-digital converter (A/D converter) with the highest spurious free dynamic range (SFDR) in its class.

The dual 16-bit D/A converter, the AD9779, offers best-in-class dynamic range and noise and distortion, while consuming up to 36% less power than competing solutions. The highly integrated interpolating dual AD9779 is designed to enable high quality conversion of the most demanding wireless standards, such as W-CDMA, CDMA2000, TD-SCDMA and WiMAX.

“The requirements of multi-channel wireless communications applications and digital predistortion architectures are driving the need for more optimized data converters that can synthesize high-quality signals at much higher frequencies,” said Dave Robertson, product line director, high-speed converters, at Analog Devices. “With the AD9779, Analog Devices is delivering a dual 16-bit DAC that offers wireless systems designers the best combination of signal processing performance, low-noise and low-power consumption for wideband signal synthesis. This combination allows communications infrastructure manufacturers to design one transceiver platform for the global deployment of multiple wireless standards.”

In addition to the AD9779, Analog Devices is introducing the AD9778 and AD9776 dual interpolating D/A converters, forming a family of 16-/14-/12-bit pin-compatible devices that allow designers to trade off performance for system cost. These devices are the newest members of ADI's TxDAC+ portfolio of D/A converters specifically optimized for the transmit signal path of communication systems.

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ADI's AD9779 IMD Performance Chart

In comparison to competing products, the 16-bit AD9779 dual D/A converter offers 4 dB lower noise, 15 dB better intermodulation distortion (IMD) and 20 dB higher SFDR at a 70 MHz output frequency, while consuming 600 mW of power at 500 Msamples/s and 1 W at 1 Gsamples/s. The device contains on-chip digital interpolation filters, a complex digital modulator and a digital mixer. These features simplify the digital interface and allow some digital signal processing functions to be moved out of the FPGA or ASIC.

As a dual D/A converter, gain and offset matching in the AD9779 is guaranteed, making the device appropriate for direct conversion or image reject architectures using an analog quadrature modulator. Integrated gain and offset calibration D/A converters enable communications equipment designers to optimize sideband rejection and local oscillator (LO) feedthrough in these architectures. A multi-D/A converter synchronization scheme simplifies clocking requirements in systems with multiple converters, allowing easier control of phase coherency. Device configuration is achieved through an easy-to-use serial peripheral interface (SPI) with an interface common to other TxDAC+ devices.

For optimized transmit signal chain performance, the analog output of the AD9779 TxDAC+ converter seamlessly interfaces to Analog Devices' analog quadrature modulators, such as the AD8349. A standard parallel interface enables straightforward connection to the AD6633 multi-channel wideband up converter with the VersaCREST crest reduction engine. The AD9779 can be driven by ADI's AD9510 high-performance clock distribution IC as part of a complete clock distribution system.

ADI's latest 14-bit, 80 Msamples/s A/D converter, the AD9444, is designed to interface to the AD6636 4-/6-channel digital downconverter to form the core of a wideband communications receiver. Together, these devices form the basis for a high-performance digital radio transceiver.

The AD9779, AD9778 and AD9776 TxDAC+ converters are sampling now and will be available in production quantities in May 2005 in a Pb-free 100-lead thin quad flat pack exposed paddle (TQFP_EP) package. The AD9779 is priced at $27.95 in 1,000-unit quantities, while the AD9778 and AD9776 are priced at $24.95 and $19.95, respectively, also in 1,000-unit quantities.

Click here for a data sheet of ADI’s AD9779.

Also being introduced today, ADI's 14-bit, 80 Msample/s A/D converter offers the highest SFDR in its class, according to the company. With wireless communications providers now carrying multiple radio standards, SFDR has become increasingly important for increasing call capacity and reducing dropped calls.

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ADI's AD9444

The first in a family of high-speed, high-resolution A/D converters optimized to improve the robustness and simplify the design of advanced 3G and next-generation 4G wireless base stations, the AD9444 provides a typical SNR of 73.1 dB and SFDR of 97 dBc with a 70 MHz input — a full 7 dB better than any other A/D converter in its class. Optimized for wireless basestation applications, its high SFDR also makes the AD9444 suited to test equipment, wireless broadband and high-end data acquisition systems.

In addition to delivering 97 dBc SFDR and 73.1 dB SNR with a 70 MHz input, the AD9444 offers typical differential non-linearity (DNL) of ±0.4, least significant bit (LSB) integral non-linearity (INL) of ±0.6 LSB, and power dissipation of 1.2 W.

The A/D converter also features parallel low-voltage differential signaling (LVDS) outputs, including an output clock, simplifying the interface to digital down-converters and reducing the potential for digital noise coupling back into the A/D converter core.

The LVDS output of the AD9444 interfaces seamlessly with the LVDS support of the AD6636 multi-channel wideband digital-down converter, which is optimized for Analog Devices' TigerSHARC digital signal processor.

The AD9444 A/D converter is shipping in production volume now. It is available in Pb-free 100-lead TQFP_EP and priced at $38.25 per unit in 1,000-unit quantities. Two evaluation boards and a behavioral model that can be used with Analog Devices' ADIsimADC modeling software support the device.

Click here for a data sheet of ADI’s AD9444.

For more information, please call 1-800-262-5643 or visit:

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