We are planning to use AD9371 or AD9375 for our application with fast settling external LO signal instead of internal LO.
Our frequency range is 4.3GHz to 5.0GHz, But in the AD9371 datasheet given as " operation for the external LO option is limited to a maximum of 4000 MHz".
1. What is the exact limitation of using external LO at our maximum frequency of 5.0GHz?
2. Why we need to give external LO inputs must be 2× the desired LO frequency?
3. Is it same for AD9375 or it will have better specs?