AD9911:  500 MSPS Direct Digital Synthesizer w/10-Bit DAC

The AD9911 consists of one complete direct digital synthesizer (DDS) that operates up to 500MSPS. In addition, there also exist three auxiliary DDS cores without assigned DACs. These auxiliary channels may be used for either spur reduction or test tone modulation.

The AD9911 incorporates an integrated high speed, 10-bit DAC with excellent wideband and narrowband SFDR. The device offers a 32-bit frequency tuning word, 14-bits of phase offset, and a 10-bit output scale multiplier.

The AD9911 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 AD9911 also supports linear sweep of frequency, phase, or amplitude for applications such as radar and instrumentation.

The AD9911 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 DDS products. Flexibility is provided by four data pins (SDIO_0:3) that allow four programmable modes of serial I/O operation. The DAC output is supply referenced and must be terminated into AVDD by a resistor or an AVDD center-tapped transformer. The DAC has its own programmable reference to enable different full-scale currents.

The DDS acts as a high resolution frequency divider with the REF_CLK as the input and the DAC providing the output. The REF_CLK input can be driven directly or used in combination with an integrated REF_CLK multiplier (PLL) up to a maximum of 500 MSPS. The PLL multiplication factor is programmable from 4 to 20, in integer steps. The REF_CLK input also features an oscillator circuit to support an external crystal as the REF_CLK source. The crystal must be between 20 MHz and 30 MHz. The crystal can be used in combination with the REF_CLK multiplier.

The AD9911 comes in a space-saving 56-lead LFCSP package. The DDS core (AVDD and DVDD pins) is powered by a 1.8 V supply. The digital I/O interface (SPI) operates at 3.3 V and requires the pin labeled DVDD_I/O (Pin 49) be connected to 3.3 V.

The AD9911 operates over the industrial temperature range of −40°C to +85°C.

Applications

• Agile local oscillator
• Test and measurement equipment
• Commercial and amateur radio exciter
• Radar and sonar
• Test tone generation