Design Of Injection Locked Coupled CMOS Terahertz Voltage Controlled Oscillator

Due to its unique characteristics in broadband,propagation and penetration,terahertz waves have a wide range of applications in the fields of broadband communication,medical imaging,radar,spectrum analysis,non-destructive testing and security inspection.As an indispensable module in the terahertz communication system,the terahertz oscillation has become one of the current research hotspots.With the increase of the circuit operating frequency,the transistor's gain decreases,quality factors of the passive devices decrease,and the parasitic effect of the interconnect lines is obvious.The above factors bring great challenges to terahertz circuit design.This dissertation discusses the oscillating source in a terahertz broadband communication system and designs a injection-locked coupled terahertz voltage-controlled oscillator based on the 40 nm CMOS process.In this paper,the circuit design,layout design,circuit and EM co-simulation are completed.And the measurement plan of injection-locked coupled terahertz VCO is provided.This THz signal source is a ring structure composed of four core oscillators and four phase shifters.The output frequency is tuned by controlling the coupling between the core oscillators.A cross-coupling structure is adopted for the core oscillator,and a cascade amplifier structure with a resonant tank is used to design the phase shifter.The phase range of the phase shifter is between 0 ? ?,so that the core oscillator works in 90° mode,which can effectively combine the fourth harmonic of the core oscillator to the output and improve the output power of the fourth harmonic.In the layout,the current capacity of the transistor interdigital metal electrode and the interconnection line was considered and the parasitic resistance of the transistor port on the circuit was calculated,and all transmission lines and interconnection lines in the circuit were EM simulated.The co-simulation results showed that the core oscillator works in 90° mode,and the transient output fourth harmonic signal swings252 m V.With the controlling voltage changes from 0 to 1.8V,the output signal frequency range is 294.9GHz ? 304 GHz.A 3% tuning range is achieved and the output power is-3.9d Bm.The phase noise of the VCO is-87.9d Bc/Hz@1MHz.This paper implements a terahertz voltage-controlled oscillator based on CMOS technology,which satisfies the requirements of the system and lays an important foundation for the development of a terahertz broadband communication system.