Communications DACs drive down to 3V systems

Analog Devices has unveiled the third generation of its industry-leading TxDAC line of transmit-quality digital-to-analogue convertors (DACs).

Analog Devices has unveiled the third generation of its industry-leading TxDAC line of transmit-quality digital-to-analogue convertors (DACs).

These three new convertors incorporate the latest advances in circuit architectures and design techniques, with the flagship device - the AD9744 - boasting the best AC and DC performance in the industry, enabling designers to meet overall system performance and manufacturing requirements in the most demanding wired and wireless communications applications.

The TxDAC family is optimised for the transmit signal path of communications infrastructure, including cable head-end systems, optical networking systems, and multicarrier 3G basestations.

Low power dissipation and 3V operation also makes them ideal for portable applications.

They are also well suited for instrumentation, test equipment, optical monitoring and optical control markets.

"This new generation TxDAC family demonstrates our continued technology development and leadership in high-speed convertors", said Kevin Kattmann, product line director for Analog Devices' High Speed Convertor Group.

"With these new devices, we are continuing our commitment to TxDAC customers, offering constant improvement in the pin-compatible family - as demonstrated by the unmatched performance and 3V operation - and by providing price-sensitive communications infrastructure customers with an affordable means for upgrading to the next generation of wireless standards".

The family includes the 14bit AD9744, the 12bit AD9742, and the 10bit AD9740.

The AD974x family offers exceptional DC performance, with integral nonlinearity (INL) and differential nonlinearity (DNL) specifications that are 50% better than anything that is available on the market.

The AD9744 has typical INL of +/-0.8LSB and DNL of +/-0.5LSB at 14bit.

A segmented current source architecture is combined with a proprietary switching technique to reduce spurious components and enhance dynamic performance.

This allows the AD9744 to provide the industry's best dynamic performance, with spurious free dynamic range (SFDR) of 83dBc and signal-to-noise ratio (SNR) of 77dB at an output frequency of 5MHz.

A high-speed, single-ended CMOS clock input supports a 165Msample/s conversion rate.

The devices have differential current outputs from 2 to 20mA and include a 1.2V temperature-compensated bandgap voltage reference.

They operate on a single 3.0 to 3.6V supply and consume 135mW.

Power dissipation can be reduced to just 60mW by lowering the full-scale current, and a sleep mode, consuming only approximately 15mW, is provided for low power idle periods.

The devices will soon be available in a 32-lead chip-scale package, which is 87% smaller than the standard SOIC package, and is the smallest package for convertors of this class.

This enables designers to reduce board space with no loss in performance.

Pin-compatibility allows designers to upgrade systems without adding significant cost, as basestation and other infrastructure manufacturers face more challenging transmit standards and strong price pressure.

Devices are sampling in 28-lead SOIC and TSSOP packages.

The AD9744, AD9742 and AD9740 are priced in 1000-piece quantities at $9.00, $6.95 and $4.95 per unit, respectively.

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