Frequently Asked Question
Is it okay to AC-couple PECL or LVDS outputs?
Generally yes, but one must be aware of the high-pass filter formed by the coupling capacitor and the input resistance of the circuit driven by the PECL or LVDS signal:
Therefore, the gain from the PECL or LVDS output to the receiving circuit input is approximately unity for f>>1/(2πRINC).
LVPECL requires near-end termination which must be before any coupling capacitor.