Signal Attenuation
High speed signal path assessments calculate the difference between the available signal power and the minimum power required for reliable data recovery. A high link margin loss occurs when the transmission channel experiences excessive attenuation due to dielectric absorption and copper roughness. This degradation reduces the reliability of high speed communications and increases the frequency of transmission errors.
Diagnostic Measurement
Network analysis tools measure the scatter parameters of the physical channel to determine the exact distribution of transmission losses. The insertion loss curve reveals how the signal attenuates across a spectrum of frequencies, allowing engineers to identify resonance points caused by circuit board vias or connector interfaces. Poor layout design can amplify these losses through impedance discontinuities that reflect signal energy back to the transmitter.
By plotting the loss profiles, signal integrity engineers can pinpoint the physical location of the board defect causing the mismatch.
Receiver Performance
Equalization circuits attempt to compensate for channel losses by boosting the high frequency components of the incoming signal. When the degradation exceeds the compensation capability of the receiver, the eye diagram closes and the bit error rate rises. This threshold defines the functional limits of the high speed serial link under test.
