Analysis of Multiline Calibration Algorithms for Various Transmission Line Types Up to 220 GHz

Multiline Thru Reflect Line (mTRL) algorithm is widely regarded as one of the most accurate and reliable calibration methods for on-wafer measurements. However, at higher frequencies it may exhibit peculiarities due to non-optimal definitions or parasitic effects. This paper presents a systematic comparative study of the NIST and TUG mTRL approaches using different transmission line types (i.e. grounded coplanar waveguides and microstriplines). Measurements are performed in three different bands from 1 to 220 GHz with probes from different vendors and compared with electromagnetic (EM) simulations. The results suggest that the NIST mTRL method becomes less reliable at banded frequency ranges especially when line lengths are not optimally selected. In contrast, the TUG mTRL method remains robust, as confirmed by measurements and simulations.