• AD9857: FUD signal

    Q 

    Subject: AD9857 Digital Up Converter and its evaluation board.
    1) The rising edge of the FUD signal would to transfer the profile registers
    content in the DDS accumulator. Why Does the FUD signal in the board change its
    state continously…

  • AD9857求助

    系统采用9857作为duc，对基带数据进行bpsk调制，目前基带数据调制，时序均正常

    采用sst的单片机模拟spi接口，对duc进行配置，示波器检查确认时序正确，可以写入00h和06h寄存器（使用profile

    0） 检查pdclk反馈是正确的，但是发现对频率控制字02--05h的配置好像就没有反应，测试单音模式（single

    tone），fud使能后明显电流加大，但是丝毫不见正弦输出，频谱仪上也是乱七八糟的

    硬件设计时数字和模拟地没有分开，输出看到了约20mv的噪声，不知正常下写07h…

  • AD9857 Iout bad levels

    I have my AD9857 with the next configuration:

    I am using AD9857 with a single REFCLK input of 146.2857MHz with very good CMOS levels.(i have diffclken connected to gnd)

    I have a 2K resistor in pin RSET.

    Iout = 39.93/RSET, So Iout level should be 20mA…

  • A way to synchronize multiple AD9857

    Hello,

    I am trying to work with two of AD9857 DDSs in a synchronized way.

    In order to do that, at the same time, REFCLK, DATA, etc,

    The problem I find is that latency of output will differ 1 PDCLK  as Figure 33 and Figure 34 in the datasheet,

    Is there…

  • How to synchronize multiple AD9857?

    Hello,

    I am trying to work with two of AD9857 DDSs in a synchronised way.

    In order to do that,

    at the same time, REFCLK, DATA etc ,

    I configure these DDSs performing an automatic synchronisation.

    The problem I find is that, after powering up them…

  • AD9857 controlled by an FPGA

    After looking at the datasheet and the evaluation oard user guide, I did find something in the engineerzone:
    http://ez.analog.com/message/29843#29843

    post #10 suggests that I issue a reset first and then toggle on of the PS lines to generate a fud internally…

  • AD9857: Producing a sinc wave with DDS

    Q 

    I want to buy a DDS Model AD9857. In features description is written -
    SIN(x)/x correction (inverse SINC function)
    Does that mean that I can also produce a sinc signal with this DDS?

     

    A 

    No - there is a sibc filter correction for the DAC…

  • My AD9857 output strength is low

    Hi Sir,

        We are using AD9857 in our DVB-T modulator board.  Now it could work, but the output of AD9857 is too low. It is -76dbm.  (Measured using a Spectrum Analyzer. ).  Could you help me? Thanks. The schematic is attached.

    • AD9857Page.pdf

  • Setting the phase of an AD9857 upconverter

    Hello,

    I am using an AD9857 upconverter in quadrature modulation mode.

    I would like to know if it is possible to set the phase of the DDS core or, alternatively, to rerset it to zero.

    Thank you

  • AD9857 Single Input levels ref clock?

    Hello;

    I can see in the datasheet of AD9857, in the Ref Clock input characteristics, the Differential Input levels. But:

    What about if the input is single? What are the levels for the Ref Clock input?

    Thank you.

    Miguel Ángel.