Investigation On140GHz CMOS On-chip Antenna

With the development of the wireless communication technology and semiconductortechnology, people have become increasingly demanding of circuit integration, and the study ofon-chip integrated antenna is becoming more and more widely. However, the traditional integratedantennas based on the PCB (Printed Circuit Board) process limit the improvement of circuitintegration. This lead to the proposition of the AOC (Antenna on Chip), and the AOC is a researchhot spot in the antenna field in recent years. AOC is a novel conception which directly integrateantenna on chip based on the CMOS. However, the complex environment, especially the presenceof the doped silicon substrate having a high dielectric constant and a low resistivity, will lead thecommon AOC work with a low efficiency. In this work, we make an effective isolation betweenAOC and the doped silicon substrate by introducing AMC (Artificial Magnetic Conductor)technology, this results in effective AOCs. Meanwhile, the center frequency of the antenna of thisstudy are60GHz and140GHz, in the current antenan study, is relatively rare.140GHz band isbetween millimeter wave and terahertz (frequency range from0.1~10THz, wavelengths between3mm~30um),Terahertz is a band which people have not yet fully understanding and using. Withthe last decade reliable terahertz sources are constantly developed, research THz communicationbegan to heat up. Compared to microwave communications, terahertz communications capacity hasbeen greatly improved, which can provide up to10Gb/s communication speed. Further terahertzbetter directionality and higher resolution, higher noise immunity and confidentiality, and arelatively shorter wavelength smaller antenna size brought about a more simple and compact, andother advantages of the circuit. Relative to the optical communications, THz communication withhigher energy efficiency and better penetration.First, We present the working principle, equivalent transmission line modal and designformulas of mushroom-like HIS (High Impedence Surface), UC-PBG and AMC without metallizedvias based on FSS (Frequency Selective Surface). We give the designs of square patch, square loopand jerusalem cross AMCs based on the above analysis which conform the standard CMOScrafts.Then, We carry on the study of why the common AOCs can’t work effectively. We find thatmain electromagnetic energy is restricted with the form of surface waves in the silicon substratehaving a high dielectric constant and a large thickness for common AOCs, and the restrictedelectromagnetic energy is mainly dissipated as heat for the reason of the low resistivity of thesilicon substrate. This lead the common AOCs work with low efficiency. Next, The CMOSprocesses which can be used in the design of AOCs are investigated, and we get the electrical parameters of each conductor layer and each dielectric layer of a particular CMOS process, theseelectrical parameters are vital for the design of AOCs. Finally, compare the on-chip antenna load onthe AMC structure with a common on-chip antenna, we proved artificial magnetic conductorstructure to improve the antenna performance advantage does exist. In order to better study, we alsoanalyzed the different number of artificial magnetic conductor and different structures of artificialmagnetic conductor.