Design Of Millimeter Wave Down Mixer Based On CMOS Technology

Nowadays,wireless communication technology has penetrated into every corner of the world and profoundly affected every field of society.Due to the demand for high speed and low delay communication,the development direction of communication technology has changed from the constantly exhausted low frequency band to a higher frequency band,such as millimeter wave.At the same time,the comprehensive consideration of cost,power consumption,performance and integration makes CMOS technology become a research hotspot.Down-conversion mixer is an important part of the receiving link of the communication system.Whether the signal frequency conversion is good or not has a great influence on the performance of the whole system.Therefore,it is of great significance to study down-conversion mixer in millimeter wave band under CMOS technology.Firstly,this thesis describes the research background and research results of MMW down-conversion mixer at home and abroad.CMOS process,active device and passive device needed in circuit design are introduced,and the basic theory,topology structure and performance index of mixer are analyzed.Then,based on the above work,this thesis uses 65-nm CMOS technology to design two down-conversion mixers working in the millimeter wave band.In order to cover the main frequency band of 5G millimeter wave communication in China,the first mixer uses Marchand balun with broadband characteristics to achieve broadband matching,and the equivalent circuit analysis of balun is carried out.The mixer uses a modified Gilbert structure and a weak inversion bias technique to achieve low supply voltage and low DC power consumption,and a trans-impedance amplifier at the output is used to improve the conversion gain.The test results show that the 3d B bandwidth of the mixer is 20～55GHz,and the conversion gain of the mixer is-0.37～2.41d B when the IF frequency is 2GHz.The LO power required by the circuit is-3d Bm and the DC power consumption is 7.48m W.The total area of the chip is 0.25mm~2.In order to further optimize the noise performance,a down-conversion mixer with the operating frequency of 35～45GHz is designed.The Gilbert structure is used in the mixer,and the introduction of inter-stage series resonant inductance reduces the influence of transistor’s parasitic capacitance,and then it optimizes the noise figure and conversion gain.The current reuse trans-conductance stage and current injection structure in the circuit are used to further improve the noise and conversion gain performance.In addition,different from the previous design,the use of transformer balun reduces the use of bias network and achieves good matching.The post-simulation results show that the noise figure of the mixer is 8.3～9.2d B,the conversion gain is-3.3～-2.3d B when the IF frequency is 6GHz.The DC power consumption is 16.9m W and the total layout area is 0.23mm~2.In this thesis,the one of two down-conversion mixers has achieved broadband and low power consumption,the other has achieved low noise,and both have small chip or layout area.It has a certain reference significance for the design of mixer with the millimeter wave band.