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Delay and Jitter in generation of HF PULSES using OSK

Question asked by roboavian on Feb 8, 2018
Latest reply on Feb 8, 2018 by KennyG

Greeting Sir,

                    I am generating HF pulses using External OSK using FPGA. The problem I am encountering is that as soon as I make the OSK pin high on AD9914, the waveform generation starts with a delay in the range of 100 ns - 120 ns and when I make my OSK pin LOW, the pulse generation stops after around 40 - 50 ns. I understand that physical hardware has its own rise-time and fall-time and that it needs time to react but if this was a constant delay I wouldn't have any problem. The problem is that I am getting a constant Jitter of 20 ns in my pulse. As you can see in the images attached. Is there any way to exterminate this Jitter? Is this an inherent Jitter of the DDS that cannot be fixed? Any help would be much appreciated.The yellow signal in this picture is my output waveform. As you can see there is a 20 ns Jitter. As each box in the oscilloscope is of 20 ns, The wave either starts one box before or after.The Green Signal in the oscilloscope is the OSK signal, and the yellow signal is the output HF waveform pulse, The Jitter is clearly visible.

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