Signal Terminators
1. What is the Core Function of Signal Terminators ICs?
Impedance Matching: Eliminate signal reflection through termination resistors to ensure that the signal is absorbed at the end of the transmission line, avoid waveform oscillation, overshoot, or undershoot caused by impedance mutation, and ensure signal transmission integrity.
Signal Integrity Optimization: In high-speed digital circuits (such as clock frequency >100 MHz or rise time <1 ns), suppress signal distortion (such as ringing, non-monotonicity), reduce timing error and bit error risk.
2. What are Signal Terminators ICs Used for?
Communication System and Bus Protocol
Used in differential signal transmission systems such as CAN, RS-485, and LVDS, match characteristic impedance (such as 120Ω, 100Ω) to suppress reflection noise.
In high-speed serial interfaces (such as PCIe and USB), reduce the impact of signal edge degradation on timing budget.
High-speed Digital Circuit
Connect the data/address bus of processors, memory, and other devices to prevent signal attenuation and reflection interference caused by long routing.
Reduce the impact of power noise and ground bounce on signal quality.
3. Implementation Form of Signal Terminators ICs
Discrete Components: such as SMD resistor arrays, need to be accurately selected according to the characteristic impedance of the transmission line (such as 50Ω, 75Ω).
Integrated Terminal IC: Some dedicated chips integrate terminal resistors, matching circuits, and driving functions to simplify PCB design and improve consistency.
4. Design Points for Signal Terminators ICs
Terminal Type Selection: Use parallel termination (Parallel), Thevenin termination (Thevenin), or active termination (Active) according to the scenario.
Layout Optimization: The terminal resistor needs to be placed close to the receiving end or the end of the signal to shorten the reflection path.