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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:

equation
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.