DAC Suggestion for UHF TX Chain

Hi all,

We are looking at combining the ADF4350 and ADL5385 to create a transmit chain covering the 200MHz-400MHz frequency range. The transmit path requires a 1.2MHZ GMSK waveform.

What would be the recommended DAC(s) to go along with this lineups? There are no requirements for multi-carrier operation; and we are looking for a dual-DAC package. We are also looking at significantly oversampling to ease the anti-alias filter between the DAC and IQ-MOD (this oversampling is currently planned before the DAC, but could be moved inside the DAC if the part allowed for it). Initially, we looked at the AD9765, but not sure if this would be good enough.


  • 0
    •  Analog Employees 
    on Nov 17, 2010 12:36 PM over 10 years ago

    For more specific details I would contact ADI through your sales organisation, as these parts are supported by our High speed converters group.

    But another approach may involve the AD9789 RFDAC.  This RFDAC can be configured for high over-sampling ratio while operating in the QDUC mode. We will check for the most appropriate baseband DAC also.

  • 0
    •  Analog Employees 
    on Nov 18, 2010 2:13 AM over 10 years ago

    The previous posting offered an RF DAC(AD9789 : 14Bit, 2400MSPS) could be considered as an alternative to a Baseband DAC & IQ Modulator(ADL5385) approach. For Baseband DAC and IQ Modulator approach, we would suggest either  AD9117/16 ( 20ma output)  or AD9717/16 (2ma output) depending on whether lower power is  important or output current close to 20ma and lower noise is more critical.

    For the detail performance of those suggested12/14 bits DAC, refer product pages at our web site( www.analog.com ).

  • You didn't mention the receive chain... there are a couple of alternatives. The AD9957, which is a DDS modulator, can create a modulated IF that you can mix into this range so you would only need a mixer and PLL/VCO. I thnk it's fast enough for 1.2 MBPS GMSK.

    Alternatively, the AD9961/3 comes in 10 and 12 bit versions and contains both the TxDACs (130 MSPS, more than fast enough) and a pair of ADCs that can be used together for I and Q baseband or a single ADC can be used for sampling an IF.

  • Thanks to all for your suggestions. We'll be looking at pairing the ADF4350 with the ADL5385 to evaluate the performance; and will look at the DAC recommendations. I'm sure we'll have more questions once we get these devices paired up. Again, thanks.