CMOS 300 MSPS Complete DDS
The AD9852 digital synthesizer is a highly integrated device that uses advanced DDS technology, coupled with an internal high speed, high performance D/A converter to form a digitally programmable, agile synthesizer function. When referenced to an accurate clock source, the AD9852 generates a highly stable frequency-, phase-, and amplitude-programmable cosine output that can be used as an agile LO in communications, radar, and many other applications. The innovative high speed DDS core of the AD9852 provides 48-bit frequency resolution (1 μHz tuning resolution with 300 MHz SYSCLK). Maintaining 17 bits ensures excellent SFDR.
The circuit architecture of the AD9852 allows the generation of output signals at frequencies up to 150 MHz, which can be digitally tuned at a rate of up to 100 million new frequencies per second. The (externally filtered) cosine wave output can be converted to a square wave by the internal comparator for agile clock generator applications. The device provides two 14-bit phase registers and a single pin for BPSK operation.
For higher-order PSK operation, the I/O interface can be used for phase changes. The 12-bit cosine DAC, coupled with the innovative DDS architecture, provides excellent wideband and narrow-band output SFDR. When configured with the comparator, the 12-bit control DAC facilitates static duty cycle control in the high speed clock generator applications.
The 12-bit digital multiplier permits programmable amplitude modulation, on/off output shaped keying, and precise amplitude control of the cosine DAC output. Chirp functionality is also included for wide bandwidth frequency sweeping applications. The AD9852 programmable 4× to 20× REFCLK multiplier circuit internally generates the 300 MHz system clock from a lower frequency external reference clock. This saves the user the expense and difficulty of implementing a 300 MHz system clock source.
Direct 300 MHz clocking is also accommodated with either single-ended or differential inputs. Single-pin, conventional FSK and the enhanced spectral qualities of ramped FSK are supported. The AD9852 uses advanced 0.35 μ CMOS technology to provide this high level of functionality on a single 3.3 V supply.
The AD9852 is pin-for-pin compatible with the AD9854 single-tone synthesizer. The AD9852 is specified to operate over the extended industrial temperature range of −40°C to +85°C.
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This page contains evaluation board documentation and ordering information for evaluating the AD9852.
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Ask The Application Engineer—33: All About Direct Digital Synthesis
(Analog Dialogue, Vol. 38, August 2004)
Single-Sideband Upconversion of Quadrature DDS Signals to the...
(Analog Dialogue, Vol. 34, No. 3, May, 2000)