I would like to use the LTC5577 at an RF frequency of 5800 MHz (150 MHz BW) but need to have the option of using a high-side LO for an IF of around 500 MHz.. The LO input will be around 6300 MHz. Which part of performance will start degrading with higher LO when we are still within RF specs. Is there any data that shows performance beyond 6GHz LO while meeting RF and IF frequency range requirements? I do have an option to run the LO a few dB higher if needed.
Sorry, we don't have high-side LO data at 5.8GHz range. However, looking at lower frequencies, high-side LO does not seem to impact performance significantly:
When LO is above 6GHz, you *may* see…
When LO is above 6GHz, you *may* see some degradation in noise and 2nd order distortion performance. I would recommend increasing LO drive level closer to 6dBm, or even higher.
It would be best to order an evaluation board and try it out under your design conditions.