Investigation of S21 magnitude extraction methodologies by using a pattern generator and sampling oscilloscope

S-parameter measurements of a digital link path are measured with VNAs or high-end TDRs. For multi-port in-situ measurements, these become inconvenient and time consuming. However, it can be handled more conveniently in the time domain (TD) by using a pattern generator and a multichannel sampling oscilloscope, which are used for eye-diagram measurements. This paper outlines and compares three methods to extract S₂₁ magnitude from the time domain measurements using a pattern generator and a sampling oscilloscope for any channel. The setup differs in terms of the input waveform and the processing. The comparison provides insight into the advantages and limitations of each method.