500 GHz 3-dB directional coupler with 38-dB isolation incorporating right-handed/left-handed coupled-line in CMOS 0.13 μm

A CMOS 3-dB directional coupler incorporating the right-handed/left-handed coupled-line on the perforated ground is presented. The composite coupled-line is constructed by the unit cell with a period of 18 μm. The guiding characteristics of the right-handed and left-handed transmission lines on the perforated ground are theoretically extracted to assist in designing the directional coupler with high directivity. The coupler prototype, which consists of seven cells, is designed at 500 GHz, and implemented by using 0.13 μm 1P8M CMOS technology. The scattering analyses show that the proposed coupler has a -3 dB coupling between 430 GHz and 570 GHz with a highest isolation of 38 dB at 482 GHz.