Frequency Switching in DDS

[sangitacp93]

Hello all,

Direct Digital Synthesis (DDS) has frequency switching ability . While trying to implement the DDS in VHDL, I got confused with the frequency switching ability of DDS. For example, I have implemented the sine wave which generates multiple waves from testbench defined. But how do I implement the switching ? Do I need to define timestamp (like 100ns) and the frequency of signal A changes to frequency of Signal B, or any other technique to do so ?

I appreciate your feedback.
Thank you

 

[FvM]

Frequency modulation or switching is done by manipulating the accumulator increment (frequency word), either asynchronous or at specific times, e.g. zero crossing.