An Improved Multimode TRL Calibration Method to 110 GHz Based on Coplanar Grounded Waveguides

The multimode thru-reflect–line (TRL) algorithm is widely used for on-wafer differential circuit calibration. This article presents the design and calibration of coplanar grounded waveguide (GCPW)-based calibration kits. Based on the original algorithm, we optimize the reflect standard symbol determination algorithm. The impedance transformation algorithm is added so that the algorithm can be applied to calibrating strongly coupled devices. An improved algorithm and the designed calibration kits enabled precise calibration from 0.1 to 110 GHz. The conventional multimode TRL algorithm line standards have a narrow calibration range and require manual selection. In this article, an algorithm for selecting line standards is proposed, which automatically selects line standards with minor errors and expands the calibration frequency of line standards. Finally, the error of the improved multimode TRL algorithm is quantitatively analyzed and discussed.