Krosstalk

Krosstalk (often spelled cross-talk) is the unwanted coupling of signals between adjacent communication or signal-carrying channels. The term is used across electronics, telecommunications, and networking to describe leakage of signals from one conductor, wire pair, circuit path, or optical channel into another, degrading signal integrity and reducing channel isolation. While many contexts use the standard spelling "cross-talk," some texts and languages prefer "krosstalk" and may treat it as equivalent.

Electrical crosstalk arises from capacitive coupling between nearby conductors, inductive coupling due to mutual magnetic fields, or shared impedances in the circuit. In high-speed copper links and printed circuit boards, this is often characterized as near-end crosstalk (NEXT) and far-end crosstalk (FEXT). Optical crosstalk occurs when light from one optical channel leaks into another due to imperfect isolation in fiber bundles, multiplexers, or waveguides, and can be exacerbated by fiber bending, splices, or connector losses.

Crosstalk is typically quantified in decibels (dB) of isolation or signal-to-noise ratio. In networking and signal integrity contexts, crosstalk reduces channel SNR, creates errors in digital transmission, and lowers achievable data rates. In audio, crosstalk manifests as leakage between stereo channels, lowering stereo imaging accuracy.

Mitigation focuses on increasing physical separation, using shielding and shielding strategies, twisted-pair or differential signaling, proper termination and impedance control, and minimizing shared return paths. In IC design, guard traces, shielding wells, and careful layout reduce coupling. In fiber and optical systems, optical isolation, filtering, and wavelength-selective components improve channel isolation.