Differential impedance measurement method of RFID transponder chips at UHF

A novel on-wafer measurement method of RFID transponder chips is presented. A comparison is made between single ended one-port, single ended two-port and differential two-port excitation. The two-port method is a flexible way of measuring chips consisting of both several individuals as well as chip types with different geometries with one and the same probe type. The theory of un-terminating and de-embedding is described and verified by measurements. A qualitative analysis is defined, which explains certain phenomena seen in communication tests performed on RFID protocol level. This is further supported by measurement results from the presented method.