A General 4-Port Solution for 110 GHz On-Wafer Transistor Measurements With or Without Impedance Standard Substrate (ISS) Calibration

Abstract

This paper presents a general 4-port algorithm that can remove on-wafer parasitics from on-wafer measurements after impedance standard substrate (ISS) calibration of system errors, or remove both system errors and on-wafer parasitics in a single step without ISS calibration. On-wafer standards are fabricated on a 0.13 RF CMOS process, and experimental data are measured from 2 to 110 GHz using an HP 8510XF system. The impact of nonideal on-wafer load standards is examined using the deembedded transistor-parameters and the extracted small signal parameters. The errors remaining after the traditional open-short deembedding are numerically evaluated, which become significant above 50 GHz. The solved 4-port network for on-wafer parasitics is indeed reciprocal despite the assumptions of ideal OPEN and SHORT, thus allowing a mathematically simpler reciprocal 4-port solution. The general 4-port solution can also be directly applied to the measured raw S-parameters to remove both system errors and on-wafer parasitics in a single step. Single-step calibration leads to reasonably accurate transistor -parameters, despite the less accurate on-wafer standards compared to precision ISS standards.