14-bit DDS to Output Triangle Waveformt at speeds >75MHz

Document created by analog-archivist Employee on Feb 23, 2016
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Do you have a 14-bit DDS chip with Triangle Output, faster than 75MHz.

 

Unfortunately our series of DDS Waveform Generator parts are limited to 10-bits
of resolution.

Only certain DDS parts can switch between a sine-wave, triangle-wave, or a
square wave output.  These parts are the AD9833/AD9834 and AD5930/AD5932. The
highest operating frequency of these parts is the A9834 at 75MHz.

However, it seems some of our higher speed DDS parts (>75MSps) like the
AD9910/AD9911 can be modified to output triangle outputs, please see the
following thread on Engineer Zone (post by DSB):

http://ez.analog.com/message/23245#23245

It is recommended to get an evaluation board to evaluate this capability.
Note, in this mode the max effective DAC sample rate is the SYNC_CLK rate or
1/4th the system clock rate.
The reason, the sweep circuitry is clocked at the SYNC_CLK rate not the system
clock.
So, the input sample rate to the DAC input (to form a triangle waveform via
Sweeper) equals the SYNC_CLK * x where x ranges from ( 1 to 2^16).
X represents the Digital ramp rate register 0x0D.

This this will produce a sampled triangle waveform, if it is required to filter
this sampled waveform it could distort the waveform at the filtered output.

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