AD9850BRSZ-REEL

AD9850BRSZ-REEL FEATURES

125 MHz Clock RateOn-Chip High Performance DAC and High Speed

AD9850BRSZ-REEL GENERAL DESCRIPTION

The AD9850 is a highly integrated device that uses advancedDDS technology coupled with an internal high speed, highperformance D/A converter and comparator to form a com-plete, digitally programmable frequency synthesizer andclock generator function. When referenced to an accurateclock source, the AD9850 generates a spectrally pure, fre-quency/phase programmable, analog output sine wave. Thissine wave can be used directly as a frequency source, or it canbe converted to a square wave for agile-clock generator applica-tions. The AD9850’s innovative high speed DDS core providesa 32-bit frequency tuning word, which results in an outputtuning resolution of 0.0291 Hz for a 125 MHz reference clockinput. The AD9850’s circuit architecture allows the generationof output frequencies of up to one-half the reference clockfrequency (or 62.5 MHz), and the output frequency can be digi-tally changed (asynchronously) at a rate of up to 23 million newfrequencies per second. The device also provides five bits ofdigitally controlled phase modulation, which enables phaseshifting of its output in increments of 180°, 90°, 45°, 22.5°,11.25°, and any combination thereof. The AD9850 also containsa high speed comparator that can be configured to accept the(externally) filtered output of the DAC to generate a low jittersquare wave output. This facilitates the device’s use as anagile clock generator function.The frequency tuning, control, and phase modulation words areloaded into the AD9850 via a parallel byte or serial loadingformat. The parallel load format consists of five iterative loadsof an 8-bit control word (byte). The first byte controls phasemodulation, power-down enable, and loading format; Bytes 2 to5 comprise the 32-bit frequency tuning word. Serial loading isaccomplished via a 40-bit serial data stream on a single pin. TheAD9850 Complete DDS uses advanced CMOS technology toprovide this breakthrough level of functionality and performanceon just 155 mW of power dissipation (3.3 V supply).The AD9850 is available in a space-saving 28-lead SSOP,surface-mount package. It is specified to operate over theextended industrial temperature range of –40°C to +85°C.

AD9850BRSZ-REEL APPLICATIONS