So when exactly is termination of a digital signal required?
In my case, I'm dealing with a 1.8V signal that comes from an FPGA. This signal connects to a high impedance input of an OpAmp. The trace on the PCB is just about 5cm (about two inches).
The maximum frequency that I'll drive this signal will be 4Mhz. Right now I have no termination in place and everything works just fine, even with the huge impedance mismatch.
I want to learn the best practice and some rules of thumb when to care about termination and when it can be left out.