The AD9775 is the 14-bit member of the AD977x pin-compatible, high performance, programmable 2x/4x/8x interpolating TxDAC+ family. The AD977x family features a serial port interface (SPI) that provides a high level of programmability, thus allowing for enhanced system-level options. These options include selectable 2x/4x/8x interpolation filters; fS/2, fS/4 or fS/8 digital quadrature modulation with image rejection, a direct IF mode, programmable channel gain and offset control, programmable internal clock divider, straight binary or twos complement data interface and a single-port or dual-port data interface.

The AD9775 can perform fS/2, fS/4 and fS/8 digital modulation and image rejection when combined with an analog quadrature modulator. In this mode, the AD9775 accepts I and Q complex data (representing a single or multicarrier waveform), generates a quadrature modulated IF signal along with its orthogonal representation via its dual DACs, and presents these two reconstructed orthogonal IF carriers to an analog quadrature modulator to complete the image rejection upconversion process. Another digital modulation mode (that is, the direct IF mode) allows the original baseband signal representation to be frequency translated such that pairs of images fall at multiples of one-half the DAC update rate.