AD9177 DDS Generate LFM Chirp


I'm looking at using the AD9177 DDS to generate LFM chirp waveform for a radar application.  Since our application is low-power, I'm interfacing it with an MSP430 uC and therefore, am using only the SPI interface and not the JESD204 interface.  When I use the SPI interface, can I still program this DDS to generate LFM chirp? If yes, is there on-chip storage for preloading different chirps and then just select which one to output? Thank you.

  • 0
    •  Analog Employees 
    on Oct 20, 2021 9:18 AM


    I moved your thread to the High-Speed DACs community. Someone here will be able to assist you.

    Best regards,


  • 0
    •  Analog Employees 
    on Oct 22, 2021 3:27 AM

    Hi alybruin,

    No, without a JESD204B/C link the AD9177 cannot generate a true LFM. May be you could use the fast frequency hopping feature to create a "chirp" of discrete steps instead? The hop can be triggered through a GPIO pin/s and the fastest hop rate (using GPIO) is around 100-120nS. The output from multiple DDS blocks (within each CDUC / FDUC) may be combined into a single DAC output. 

    You may also consider sweeping the input device clock across some range. If the rate is slow enough the device can maintain DLL lock, and the output will track the frequency offset.    

    Would this be possible or do you need a true LFM? across what range? 


  • Hi Landsman,

    Thank you for the response.  Do you have any DDS with DAC > 6GSPS operating in SPI interface that can generate true LFM chirp? Thanks.