Once the extracted S-parameters have
been verified as causal and passive, the S-parameter plots should be inspected. It
is recommended to check for the following:
- Insertion Loss: The single-ended insertion loss is recommended
to stay within 0 to 10dB up to 3 times the Nyquist frequency of operation. For
example, if the target frequency is 8Gbps (4GHz Nyquist), the single-ended
insertion loss should stay under 10dB up to 12GHz.
- Return Loss: The single-ended return loss is recommended to be
less than 15dB up to 3 times the Nyquist frequency.
- Near and Far end crosstalk (FEXT/NEXT): The FEXT and NEXT are
recommended to be under 25dB for frequencies up to 3 times the Nyquist
frequency