The investigation of the signal radiation mechanism of different GSG‐pads connection methods

GSG‐PADs are mostly used structures in Integrated Circuits design. As the operating frequency increases, the coupling effect between the input and output GSG‐PADs is enhanced significantly. This causes signal energy leakage and impacts on the performance of adjacent devices in the system. Beyond microwave frequency, the coupling effect between the input and output of the GSG‐PADs is not only negligible but also varies in magnitude with respect to the connection methods of the GSG‐PADs in the circuit. Therefore, investigating the signal radiation properties of different GSG‐PADs connection methods is essential. Hence, three structures with different input and output ground PAD connection methods have been experimented. Based on the theoretical analysis of the electromagnetic field distribution between the pad network, a corresponding equivalent circuit model has been developed for the three structures. To validate the proposed model, the test structures were fabricated in 0.18 μm CMOS process and measured up to 67 GHz. The root‐mean‐square error (RMSE) of the magnitude of return loss S11 and that of insertion loss S21 are less than 0.013 and 0.003, respectively, when the measurement result is compared with the performance results of the proposed model. Finally, establish the complete model of the DUT and test pads to further verify the accuracy of the proposed two‐port GSG‐PADs model. Hence, the findings of the investigation can provide a theoretical basis for optimizing related layout in integrated circuit design.