Design Of Tera Hertz Oscillator Based On Standard CMOS Process

Due to its unique properties and position in the spectrum,terahertz wave has a variety of potential applications.Such as,communication,electronic warfare,radar,electromagnetic weapons,astronomy,medical imaging,nondestructive testing,environmental monitoring and safety inspections,et al.In recent years,high-speed wireless communication system tends to get broader band,higher integration and lower cost.Therefore,the design of terahertz-wave communication system has become one of the hot topics.At the same time,the CMOS process is widely used in communication system,because of its high integration and low cost.But there is still a lot of questions need to be solved,such as the limit of speed,large power consumption and the limit of frequency.Therefore,how to get stable,high frequency terahertz radiation becomes a key content of the study of Terahertz wave.This thesis designed a CMOS THz oscillator with standard CMOS process based on LC resonance principle.The main achievements of this thesis are as follow.(1)A negative resistance structure with frequency selective feature was proposed.In the specific frequency range,the designed circuit structure can not only generate negative resistance beyond its resonance frequency,but also further pushes it to higher frequency by lowering the overall tank inductance.(2)By combining this structure and the conventional cross-coupled pair,a new differential THz oscillator configuration was constructed.This oscillator has many advantages of high frequency,low power consumption,low cost and small chip area.(3)Through comparison and analysis of different parameters and different structures of the oscillator,an optimal structure was obtained,and then the layout and post simulation were performed.(4)Because the effects of parasitic elements become very important in the terahertz frequency circuit,the passive devices,such as inductors,capacitors and key signal lines,are simulated by HFSS in order to ensure the circuit performance and the simulation accuracy.The multi-port S parameters were imported into Cadence to achieve hybrid simulation.The simulation results are more precise than the traditional post-simulation results.The designed oscillator can operate at a fundamental frequency of about 140 GHz,which is higher than the cutoff frequency of CMOS device.The simulation results indicated that the designed oscillator has a amplitude of-18.8 dB,and a phase noise of-88.6 dBc/Hz at 1 MHz,showing that the oscillator achieved good performance.The oscillator designed in this thesis is expected to be used in THz communication system.