How can we reduce signal reflection?
Another important technique to reduce the reflection noise is by using damping resistors in series near all driving signal sources with fast rise/fall times. This is also known as a snubbing resistor. Any signal reflection that occurs will be quickly attenuated by each pass through the resistor.
When there is no reflection in transmission line?
When a transmission line is terminated in its characteristic impedance (Zo) there is no reflected signal. All of the incident signal is transferred to the load, as shown in the following graphic. There is energy flowing in one direction along the transmission line.
Why do reflections occur in a transmission line?
The first thing to remember is that reflections in transmission lines occur due to impedance discontinuity. A signal on a uniform transmission line encounters a constant impedance ‘Zc (V/I)’ at all locations on the line and the signal travels as desired along it.
Why does impedance discontinuity in transmission lines really matter?
The greater the discontinuity in the characteristic impedance, the higher the signal reflection. This means the signal distortion is higher as well. As such, try and keep impedance discontinuities as minimal as possible. Both in terms of amplitude and time. Read: why controlled impedance really matters.
Why are PCB traces and transmission lines the same?
Any variation or discontinuities to the impedance causes signal reflection and distortion. This phenomenon is equally true for PCB traces and transmission lines. The reason for this is that the physical wavelength of a high-frequency signal is very short. For that reason, PCB traces exhibit the same characteristics.
What causes a discontinuity in a return signal?
Splits in return signals: A high-frequency signal follows the path of lowest impedance, which is directly under the signal trace, often in a ground plane. Any physical feature in the return line or ground plane that forces the return signal to deviate from this route will create a discontinuity.