5 Assessing Impact on Signal Integrity

Introducing an additional component such as a multiplexer into the signal path can impact the signal integrity and performance of the system, and this impact needs to be measured and quantified.

Scattering-parameters, or S-parameters, provide a framework for describing networks based on the ratio of incident and reflected microwaves. These S-parameters are useful for characterizing linear, high-frequency circuits. S-parameter analysis provides information about return loss and insertion loss specifically to compare the signal integrity of FPD-Link SerDes with and without a multiplexer.

Return loss is the ratio of the reflected signal to the launched signal. Insertion loss is a measure of the transmitted signal attenuation. Higher return loss and lower insertion loss translates to higher signal integrity.

Figure 6-4 shows the reconfiguration of the signal path with the addition of the multiplexer.