Texas Instruments' Latest DAC Targeted at 3G and 4G Communications Applications
(Product News, 24 Apr 2008)
Texas Instruments Inc. (TI) has released its latest 16-bit, dual channel digital-to-analog converter (DAC) that features 800MSPS and is designed for wireless base stations, software-defined radio applications and multi-frequency test equipment. The DAC5688 expands on TI¡¯s portfolio of full-featured DACs and represents a 67 percent space reduction over the previous generation. Available in a 64-pin 9x9mm 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.
The DAC5688 also allows for more exact frequency placement, superior linearity, noise crosstalk and PLL phase noise performance. An optional frequency mixer with a 32-bit numerically controlled oscillator (NCO) runs up to 800MHz, 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.
The DAC5688 dual CMOS data bus provides 250Mbps input data transfer per DAC channel. In addition, 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 80dB stop-band attenuation.