资 源 简 介
The AD9772A is a single-supply， oversampling， 14-bit digitalto-analog converter （DAC） opTImized for baseband or IF waveform reconstrucTIon applicaTIons requiring excepTIonal dynamic range. Manufactured on an advanced CMOS process， it integrates a complete， low distortion 14-bit DAC with a 2× digital interpolation filter and clock multiplier. The on-chip PLL clock multiplier provides all the necessary clocks for the digital filter and the 14-bit DAC. A flexible differential clock input allows for a single-ended or differential clock driver for optimum jitter performance. For baseband applications， the 2× digital interpolation filter provides a low-pass response， thus providing as much as a threefold reduction in the complexity of the analog reconstruction filter. It does so by multiplying the input data rate by a factor of 2 while suppressing the original upper in-band image by more than 73 dB. For direct IF applications， the 2× digital interpolation filter response can be reconfigured to select the upper in-band image （that is， the high-pass response） while suppressing the original baseband image. To increase the signal level of the higher IF images and their pass-band flatness in direct IF applications， the AD9772A also features a zero-stuffing option in which the data following the 2× interpolation filter is upsampled by a factor of 2 by inserting midscale data samples. The AD9772A can reconstruct full-scale waveforms with bandwidths of up to 67.5 MHz while operating at an input data rate of 160 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 technique to reduce spurious components and enhance dynamic performance. Matching between the two current outputs ensures enhanced dynamic performance in a differential output configuration. The differential current outputs can be fed into a transformer or a differential op amp topology to obtain a single-ended output voltage using an appropriate resistive load.
