how to let ad9910 output a train of  pulsed sinusodial waves

Discussion created by JiongWu on Sep 2, 2016
Latest reply on Sep 3, 2016 by JiongWu

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