AD9774

The AD9774 is a single supply, oversampling, 14-bit digital-to-analog converter (DAC) optimized for waveform reconstruction applications requiring exceptional dynamic range. Manufac-
tured on an advanced CMOS process, it integrates a complete,low distortion 14-bit DAC with a 4· digital interpolation filter and clock multiplier. The two-stage, 4· digital interpolation
filter provides more than a six-fold reduction in the complexity of the analog reconstruction-filter. It does so by multiplying the input data rate by a factor of four while simultaneously suppressing the original inband images by more than 69 dB. The on-chip clock multiplier provides all the necessary clocks. The AD9774 can reconstruct full-scale waveforms having bandwidths as high as 13.5 MHz when operating at an input data rate of 32 MSPS and a DAC output rate of 128 MSPS.

The 14-bit DAC provides differential current outputs to support differential or single-ended applications. A segmented current source architecture is combined with a proprietary switching tech-nique to reduce spurious components and enhance dynamic per-formance. Matching between the two current outputs ensures enhanced dynamic performance in a differential output configura-tion. The differential current outputs may be fed into a transformer or tied directly to an output resistor to provide two complementary,single-ended voltage outputs. A differential op amp topology can also be used to obtain a single-ended output voltage. The output voltage compliance range is nominally 1.25 V.