Cryogenic CMOS Device Modelling And Research Of Ring Oscillator

With the development of quantum computing,the number of qubits required for quantum computers increases,thus resulting in the wiring requirements between the cryogenic quantum processor and the room-temperature read-out and control system becoming complicated,expensive and unreliable.Cryogenic CMOS technology offers a scalable and integrated solution for quantum device interface fabrication.In this thesis,we mainly study CMOS device and circuit cryogenic operations.We demonstrate a compact model of cryogenic CMOS and a kink effect correction model.Besides,we proposed an optimization method for the performance of cryogenic circuits.The main content of this thesis include:1.Brief introduction to the background and concepts of quantum computing,the latest process of cryogenic CMOS and its application in quantum computing.2.Introductions to the basic concept of MOSFET,the parameters and equations in BSIM3v3 model,the typical structure,principle and oscillation criteria of ring oscillator and Hajimiri's phase noise model.3.Emphasis on the variation of CMOS cryogenic characteristics and the electronic transport in the inverse layer at cryogenic temperatures.Analysis on the nonlinear abnormality induced by impurity freeze out.Discussion on the temperature dependence of the main short channel effects.4.Measurements and characterization of SMIC 0.18?m CMOS technology at liquid nitrogen temperature(LNT)and liquid helium temperature(LHT).Discussion on the temperature dependence of device performance based on the measured data.5.Parameter extraction and optimization based on the BISM3v3 model.We proposed a cryogenic compact model and a kink effect correction model,which can eliminate the irregularity in ? characterization caused by kink effect6.A CMOS ring oscillator with performance optimization based on the cryogenic device model is proposed.Discussion on the influence of temperature reduction on delay time per stage,power dissipation and phase noise.A optimization method is proposed and verified by simulation result.The main innovations of this thesis:1.Characterization of SMIC 0.18?m CMOS technology at LNT and at LHT.Analysis on the temperature dependence of device performance.Compact model at 77K and 4.2K for the SMIC process.The SPICE model can be used in the EDA tools.The modelling method provides a calibration approach for a variety of different process nodes and temperature intervals.2.A correction model for the kink phenomenon at 4.2K is proposed.A nonlinear resistor in series with substrate is added to the cryogenic model to simulate the self-polarization of the bulk.The proposed correction model proceeds the fitting precision of the cryogenic compact model.3.Demonstration of the designed CMOS ring oscillator based on the cryogenic model.Forward body biasing(FBB)is proposed to optimize the performance of the circuits and can be applied in the design of any other cryogenic circuits.