how to let ad9910 output a train of  pulsed sinusodial waves

Hi, everyone.

Recently, I use a Xilinx FPGA(Spartan6-lx9tqg144) to control the ad9910. I let the AD9910 work in the DRG mode, and I got the DRG mode work, realizing the freqency sweep from 200MHz to 250MHz.

furthermore, I wanna to get the following waves, but I do not know how to make it.

Let Ti(i=1,2,3,4,5...) denote the time duration

T1 :  0-1us , AD9910 output a  200MHz sinusodial wave
T2 :  1-10us, AD9910 output none
T3 :  10-11us, AD9910 output a 200MHz sinusodial wave
T4 :  11-20us, AD9910 output none
T5 :  20-21us, AD9910 output a 202MHz sinusodial wave
T6 :  21-30us, AD9910 output none
T7 :  30-31us, AD9910 output a 202MHz sinusodial wave
T8 :  31-40us, AD9910 output none
......
The process may repeat from 200, 202, ... 249, to  250 MHz

(1) I found that, the maxium speed of the Serial Port of AD9910 is 70Mbps. that means, in 1us, 70bits are transmited at the most.
If I use the ASF Register to control the Amplitude, I should send
8+32 bits(Phase One 8bits, and Phase two 32bits) via the SPI protocol
Does it  mean that it is hard for us to update the registers in 1us?

(2) If I use the parallel data mode, Can I make it?

(3)And I found that,
If I use the ADI's AD8180(a multiplex chip, which has a 5ns channel switch time), Maybe I can control the output, but I am not so sure.

Because, I currently use the prototype board, I wanna to know How to use the AD9910 to Control the output amplitude?


Any advise are appreciated.
Thank you

JiongWU

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  • Hi, Kenny

    Thank you for your detailed instructions guide.

    Firstly, I test the 1us ON and 1us OFF for the 202 MHz sinusoidal wave

    As you can see from the picture below. The time grid is 400 ns, and the sinusodial wave 1us tone, 1us quiet

    I can see the overshoot of the sinusodial wave when it begin to show. 

    And Could I omit the 'overshoot" of the wave as you can see from the picture below?

    Only I set the trigger level  above the normal amplitude could I get the stable display in the Tek's oscilloscope.

    If it is a normal phenomenon, I will move forward to test the other instructions that Kenny had already described above.

     

Reply
  • Hi, Kenny

    Thank you for your detailed instructions guide.

    Firstly, I test the 1us ON and 1us OFF for the 202 MHz sinusoidal wave

    As you can see from the picture below. The time grid is 400 ns, and the sinusodial wave 1us tone, 1us quiet

    I can see the overshoot of the sinusodial wave when it begin to show. 

    And Could I omit the 'overshoot" of the wave as you can see from the picture below?

    Only I set the trigger level  above the normal amplitude could I get the stable display in the Tek's oscilloscope.

    If it is a normal phenomenon, I will move forward to test the other instructions that Kenny had already described above.

     

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