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Dual-channel DAC delivers enhanced performance for 3G, 4G communications

Dallas, Tex. — Texas Instruments Inc. (TI) has introduced a 16-bit, dual-channel, 800 MSPS digital-to-analog converter (DAC) for wireless base stations, software-defined radio applications and multi-frequency test equipment. Building on the design of the DAC5687, the new full-featured DAC5688 represents a 67 percent space reduction over the previous generation.

Offered in a 64-pin, 9 x 9-mm QFN package, the DAC5688 features enhanced performance to support existing 3G applications including WCDMA and TD-SCDMA, and emerging 4G applications including WiMAX and LTE. For example, for an output frequency of 70 MHz, the device achieves 81 dBC ACLR for a single-carrier WCDMA application.

To further enhance performance in communications design, the DAC5688 allows for more exact frequency placement, and is said to deliver superior linearity, noise crosstalk and PLL phase noise performance. An optional frequency mixer with a 32-bit numerically controlled oscillator (NCO) runs up to 800 MHz, enabling more exact frequency placement. A digital inverse SINC filter compensates for natural DAC SIN (x)/x frequency roll-off.

In addition, the digital quadrature modulator correction (QMC) feature allows IQ compensation of phase, gain and offset to maximize sideband rejection to create a flatter pass band. An integrated 2x-32x clock multiplying PLL/VCO offers lower jitter and four times the multiplying range over the DAC5687. This extended range can enable designers to operate with simpler external clocking, reducing complexity and cost, TI said.

To increase flexibility, the DAC5688 dual CMOS data bus provides 250 Mbits/s input data transfer per DAC channel. Several input data options are available including dual-bus data, single-bus interleaved data, even and odd multiplexing at half-rate, and an input FIFO with either external or internal clock, which eases interface timing. Input data can be interpolated two, four or eight times by on-board digital interpolating FIR filters with greater than 80 dB stop-band attenuation.

TI also offers a suite of easy-to-use evaluation modules (EVMs) and tools for the DAC5688 to speed development time.

Pricing: The DAC5688 is available now in a 64-pin quad flat no-lead (QFN) package and is priced at $29.95 in quantities of 1,000.
Availability: Samples and EVMs are available at www.ti.com/dataconverters.com
Product information: DAC5688 and wireless infrastructure solutions

Texas Instruments , 1-800-477-8924, www.ti.com

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