(I hope this is not regarded a "shopping or buying recommendation" question - in my opinion it is not).
In order to split a larger project into more tractable and flexible sub-blocks I create two PCBs (motherboard/daughterboard).
This is a very common setup in the digital world (PAM2-PAM4) and there are high-end connectors for high speed digital (Samtec, FMC).
However, in my project I also need to "flawlessly" connect RF signals between the boards. In summary - these connections have to be made between the boards:
- ground plane, power (easily solved)
- high speed digital, ~100 MHz, ~50 I/Os (easily solved with Samtec connector)
- Analog clock, ~200 MHz
- 4x RF signals, up to 3 GHz
For 3-4 I would use SMA connectors - if it would not be a daugher board. However, I would prefer a more solid connector - ideally just one for 1-4.
I found RF board-to-board connectors but they tend to be single signals. Even if I could get an RF connector with multiple signals, physical alignment together with an FMC connector for the digital lines is painful.
So I am really looking for a board-to-board connector solution that faithfully connects 1-4.
If I can use high-speed digital connectors also for the RF signals - are there any issues or disadvantages using them compared to SMA, e.g. insertion loss, return loss/matching, isolation? Or stated differently: Why are these connector usually not used for carrying RF signals?