The AD9959 consists of four direct digital synthesizer （DDS） cores that provide independent frequency， phase， and amplitude control on each channel. This flexibility can be used to correct imbalances between signals due to analog processing， such as filtering， amplification， or PCB layout-related mismatches. Because all channels share a common system clock， they are inherently synchronized. Synchronization of multiple devices is supported. The AD9959 can perform up to a 16-level modulation of frequency， phase， or amplitude （FSK， PSK， ASK）。 Modulation is performed by applying data to the profile pins. In addition， the AD9959 also supports linear sweep of frequency， phase， or amplitude for applications such as radar and instrumentation. The AD9959 serial I/O port offers multiple configurations to provide significant flexibility. The serial I/O port offers an SPIcompatible mode of operation that is virtually identical to the SPI operation found in earlier Analog Devices， Inc.， DDS products. Flexibility is provided by four data pins （SDIO_0/SDIO_1/ SDIO_2/SDIO_3） that allow four programmable modes of serial I/O operation. The AD9959 uses advanced DDS technology that provides low power dissipation with high performance. The device incorporates four integrated， high speed 10-bit DACs with excellent wideband and narrow-band SFDR. Each channel has a dedicated 32-bit frequency tuning word， 14 bits of phase offset， and a 10-bit output scale multiplier.