On Mon, Sep 2, 2019 at 09:49 PM, Jerry Gaffke wrote:
When operating at 600mhz, we're beyond the maximum frequency
that the Si5351 can produce. So CLK1 sends out a 200mhz
square wave to the DUT, and we mix that with CLK0 at 200.00166 mhz.
The third harmonic of CLK0 is 600.005 mhz, and it is now
only the third harmonics of CLK1 and CLK0 that produce
a 5khz mixing product.
You are explaining well, except the SW uses above 300MHz the 3rd harmonic of one clock and the 5th harmonic of the other clock to avoid detecting the 3rd harmonic of the mixing product of the 1st harmonics of the clock's
Example 200MHz + 200.00166MHz produce from 1st harmonic 1.66kHz which will include a certain amount of 3rd harmonic at 5kHz.
Using 200MHz + 120.001MHz produces only 5kHz when their 3rd and 5th harmonic combine
