We are using a PNA-X and a probe core to test an Integrated circuit. The IC has differential inputs and differential outputs. For reference, the IC inputs are on Ports 1 and 3, and the IC outputs are on 2 and 4.
Due to a high amount of loss on the board and in the probe core, we want to calibrate to the pins of the probe core. We have purchased an appropriate ISS to do this work.
Our problem is that we would like to do a 4-port calibration; however a 4-port calibration requires a minimum of 3 thru connections. Our probe core + ISS only supports a thru connection between ports 1 and 3 or between ports 2 and 4. The ISS some cross thru structures, but due to our fixed probe core dimensions, we cannot use these.
Is there a way to apply one 2-port calibration to ports 1 and 3, and then to apply another 2-port calibration to ports 2 and 4? Since there is very little interaction between input and output ports on the IC, this would be sufficient for our needs.
Or, is there a better method that I don't know about? We can use PLTS if that provides a better work-around.