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DDS recommendations.

Charlie Cameron
Prodigy 10 points

Other Parts Discussed in Thread: DAC3484, DAC37J82

Hello,
 
We are looking for recommendations for a DDS that can meet our specifications. Our application is an ultrasonic transmitter.
 
We want to avoid parallel and LVDS interfaces if possible and would like to understand the alterrnative components outwith the AD9913 family, as we have previously encountered some issues in the logical function of this chip. We are particularly interested in DDSs that are:
  • Have a good degree of control for the engineer/programmer.
  • ≥150Msps
  • ≥10-bit
  • Have good/accurate performance generating waveforms below 100MHz
  • Ideally low power consumption
 
Could you please suggest some suitable DDSs from your products that may fulfil our requirements?  
I would like a DAC or DDS - DDS is preferable because most suitable DACs require a JESD204B or parallel interface
 
Thank you for your time and assistance,
Charlie
  • 0
    TI__Expert 3700 points

    Hey Charlie, 

    A few of our DAC's with digital up converters can up convert a constant value with their built in NCO's. A feature to look for is serial data mode, where a SPI register can be programmed to send a constant DC value to a DUC (digital up converter) From there this will be multiplied with an NCO leading to a sine wave with no JESD/LVDS signal necessary. 

    There is the DAC3484 (1.25GSPS, 16 bit, with a 32 bit NCO). 

    There is also the DAC37J8x (1.6GSPS, 16 bit with a 48 bit NCO). 

    Both parts have a sifdac feature which does what I described. The 48 bit NCO of the DAC37J8x will allow for much higher frequency resolution than the 32 bit of the DAC3484. If the customer needs to generate a very precise frequency, they will want to use a 48 bit NCO. 

    An easy equation to determine frequency resolution is Sample Rate (SPS)/2^(NCO bits) So the frequency resolution of a DAC3484 @ 1.25GSPS is around 0.3Hz. The frequency resolution of a DAC37J82 @ 1.6GSPS is 4.44uHz. The frequency resolution defines the steps between the achievable frequencies. 

    Neither part will need their high speed interface to be online (LVDS for DAC3484 and JESD for DAC37X8x). 

    Regards, 

    Matt