Basebandtermin

Basebandtermin, often rendered in English as baseband termination, is the practice of terminating a baseband transmission line at its far end to minimize signal reflections and preserve signal integrity. In baseband signaling, where data modulates a signal occupying a broad frequency range from near DC upward, improper termination can cause reflections, overshoot, and timing errors. Termination is typically achieved by presenting the line with a resistor network that matches the line’s characteristic impedance.

Common methods include end termination using a resistor equal to the line’s characteristic impedance (parallel termination) placed at the far end, or series termination using a resistor near the source to damp reflections. Thevenin termination uses a resistor network to present the correct impedance while providing appropriate biasing for the driver. In some cases, active or switched termination is used to adapt to changing loads or line conditions.

Applications of baseband termination include baseband video and audio cabling, older coaxial baseband networks such as certain Ethernet implementations, and digital buses on printed circuit boards where signals occupy the baseband spectrum. In modern systems, on-chip or on-board termination often replaces discrete end-term resistors when impedance is well controlled; in longer or mixed topology links, proper termination remains essential for signal quality.

Design considerations include choosing the proper impedance (often 50, 75, or 100 ohms, depending on the cable), data rate, frequency content, cable length, and the reflection coefficient. Termination can introduce static loading and power dissipation, so designers balance accuracy with efficiency. Without termination, reflections can distort timing and amplitude, reducing reliability in high-speed or long-distance baseband links.