far end receiver termination

[jdshah]

I come across the term far end receiver termination with differential signal very often. Can anybody explain what is far end receiver termination and how it is detected in simple terms

 

[betwixt]

In the case of differential data lines, it is normally just a resistor wired between the lines at the furthest away point from the device producing the signals. It's purpose is to match the impedance of the driver wires so that all the energy is absorbed at the far end. Without it, there is a risk that some of the signals will reflect back along the wires and distort the waveform, degrading the signal integrity.

Detecting it is just a case of measuring the resistance across the wires at the sending end, ideally with all the power turned off. Typical receivers will have an input resistance of several K Ohms but the terminating resistor will only be a few hundred Ohms at most so you can judge whether it is present by the resistance you measure.

Brian.