Differential de-embedding methodology for on-board CPU socket measurements

This paper describes a methodology that accurately deembeds the test structure from the socket and demonstrates valid results up to 15 GHZ. The test structure mnsists of a probe launch and microstrip line to access the socket at the PCB side, and a probe launch and plated through hole (PTH) via on a top test interface board to au%ss the top of the socket. In order to characterize the pure socket performance excluding the performance deterioration from the PTH vias, those launchers are to be deembedded. The deembedding methods described in this work are based on 2- and 4-port ABCD parameters. The methods were extensively applied to various CPU sockets in order to extract the singleended and differential socket S-parameter data.