We are using eval board for the HMC363S8G and have some noise issues at lower frequencies. The performance is good at input frequencies above 100 MHz, but when I lower my input frequency to 30 MHz (3.75MHZ output) I start to see spurs above the noise floor at various frequencies (11.25MHz, 18.75MHZ, and 26.5MHz) these are not expected. My fundamental is -40dB. Input level is at 4dBm. Further, when I decrease my input frequency to 16MHz, I see no output spectrum other than white noise.
Can you help explain what I am doing wrong?