120-GHz On-Chip Folded Dipole Antenna With Integrated Artificial Magnetic Conductor Structures

A 120-GHz folded dipole antenna including artificial magnetic conductor (AMC) structures is proposed to improve antenna gain and reduce the radiation pattern size on the standard 65-nm CMOS process. The proposed AMC structures designed in a square cushion array are constructed between the ground plane and the radiation pattern of the antenna for minimizing the signal leakage to a Si substrate. The physical size of the proposed antenna is reduced by the proposed AMC structures which change the substrate characteristics at the resonant frequency of the AMC. The ground plane of the antenna is located at the bottom of the substrate with a thickness of300 $\mu \mathrm{m}$, and the radiation patterns (a) and AMC structures of the antenna are designed in the highest metal layer (M9) and the lowest metal layer (M1) of the 65-nm CMOS process, respectively. At a center frequency of120-GHz, the proposed antenna including an $11\times 5$ AMC array showed an antenna gain of1.6 $\mathrm{d}\mathrm{B}\mathrm{i}$, a radiation efficiency of 51%, a 10- dB bandwidth of 10.1 GHz, and a vertical/horizontal 3-dB beamwidth of 147°/113° in the simulation results using ANSYS HFSS. The proposed antenna exhibited a size reduction of 26% compared to the conventional antenna.