De-embedding of On-wafer Noise Measurements.pdf

Technical Report R2000-1005 ISSN 0908-1224 De-embedding of On-wafer Noise Measurements 19th July 2000 Christian Rye Iversen E-mail: cri@kom.auc.dk RF Integrated Systems Circuits (RISC) group, Institute of Electronic Systems Aalborg University Niels Jernes Vej 12 DK-9220 Aalborg, Denmark Technical Report R2000-1005, 19th July 2000. RF Integrated Systems and Circuits (RISC) group, Aalborg University, Denmark. IVERSEN: DE-EMBEDDING OF ON-WAFER NOISE MEASUREMENTS Page 1/11 De-embedding of On-wafer Noise Measurements Christian Rye Iversen ABSTRACT To obtain accurate noise parameters of on-chip devices it is important to remove the influence of the embedding measurement fixture. This report describes a procedure for de-embedding of on-wafer noise measurements. The procedure is intended for device measurements using a ground-shielded test fixture, and assumes that the forward coupling in the fixture and the dangling leg impedance both are negligible. The report also describes how two-port noise parameters can be converted into input noise voltage and current which is often required for noise modeling purposes. I. DE-EMBEDDING PROCEDURE The noise parameter de-embedding procedure described in this report is minded for measurements using the ground-shielded fixture by Kolding et al. [1]. The ground-shielded fixture is preferable over non-shielded fixtures for high frequency s-parameter measurements as well as for high frequency noise measurements. For high frequency noise measurements the advantage is primarily that the fixture parasitics are almost purely capacitive with only negligible resistive effect. The fixture thermal noise contribution is thus very limited. Furthermore the forward coupling and dangling leg impedance are both negligible, which simplifies the noise parameter de-embedding procedure. As mentioned, this de-embedding procedure makes two assumptions compared to the full fixture model mentioned in [1]: (I) The dangling leg impedance is negligible, i.e. |Zs|