The Design Of Terahertz Varactor-free Vco Based On Silicon Germanium Process

Due to the special position of the terahertz band in the electromagnetic spectrum,it has many superior characteristics and important value of academic and application in related research fields.Voltage controlled oscillator(VCO)can be used to achieve fast frequency tuning of phase-locked loop(PLL)and other circuits.It is widely used in satellite communication terminals,base stations,radar,digital wireless communication and other circuit systems.VCO is an important part of the radio frequency integrated circuit and influences the performance of the circuit system.Compared with Ga As and In P,SiGe BiCMOS has competitive advantages in process maturity and integration,and has cost advantages as one of conventional Si processes.Therefore,VCO is generated in this dissertation based on SiGe BiCMOS process by using electronic methods.The goal is to achieve tunable terahertz signals around 260 GHz.This dissertation details the basic structure of the oscillator and the realization method of the terahertz oscillator.Besides,it introduces the design ideas of the transmission lines and the transformer,and the points for attention in the layout design.The core circuit of the terahertz VCO is composed of a differential pair colpitts oscillators to realize the push-push oscillator structure,so that the synthesized signal is the second harmonic of the oscillation signal.The tuning structure of the terahertz VCO innovatively adopts the non-varactor structure.The tuning structure includes a transformer,a base RL degenerated structure.This dissertation presents the circuit design,layout design and joint simulation of the terahertz non-varactor VCO.The joint simulation results show that the center frequency of the VCO is257.9GHz.And the output power is around-5.0dBm.The DC-RF efficiency is 0.37%.The phase noise at 1MHz frequency offset is-88 dBc/Hz.And tuning range of the VCO is from 255.9GHz to260.1GHz.