I want to use the LMX2485 as a local oscillator input to a mixer and generate frequencies in the range of 219 MHz to 445 MHz. I'm trying to reduce part count as much as possible, so would it be appropriate to either ground or not connect the IF input pins? Because I don't want to use the entire range of the chip, do I need 2 external VCOs like in the eval board or can I get away with one?
Hunter,
For the IF side, float the input pins and never connect output pins. Power these down in software.
Also, you need to supply power to the IF supply pins as well, although you probably don't need as many bypassing capacitors.
Regards,
Dean