help on Music Synthesizer

The key notes are related to the phase increment which is required to drive a pointer for direct digitial synthesis, shortend "DDS". See the wiki for this. According to the sample speed of the FPGA synthesizer module, a pointer is continously increased- the larger the value, the higher the freqency.

But a remark:

For musical applications DDS is not sufficiant. Apart from a very fine resolution and interpolation - phase dithering and filtering has to be applied in order to obtain good sine waves to derive harmonics and realistic generic waves from it. If you do this correctly the size of design becomes large and thus expensive quickly. I prefer VA Modelling for sound synthesis.

http://www.96khz.org/htm/synthesizerstructure.htm