Design Of Broadband Microwave Mixing Unit Based On CMOS Process

In recent years,people's network life has become more abundant,and wireless communication has been well developed,especially the proposal of 5G millimeter wave communication,which has pointed out the direction for the development of communication.In addition,CMOS technology has become the first choice for 5G millimeter wave chips because of its low cost and high integration.Therefore,this article conducts in-depth research and exploration for the indispensable mixer module in the millimeter wave chip.First of all,this paper discusses the transmission line theory and port network of microwave circuits in order to solve the problems of microwave circuit routing and port network analysis based on the research background of mixers at home and abroad.Then it analyzes the basic theory of the mixer,including the working principle of the mixer,two commonly used classification methods,and various performance indicators of the mixer.Based on the previous basic knowledge,a broadband mixer with high isolation is designed for the bandwidth problem of 5G millimeter wave communication.The mixer uses a standard 65 nm CMOS process,takes advantage of passive double-balanced wide bandwidth and high isolation,and uses a common source buffer stage with Q-reduction technology to compensate the gain for the intermediate frequency to achieve a high intermediate frequency bandwidth.Then the high linearity 3:3 passive balun is converted into a single-ended signal,which ensures that the linearity will not be deteriorated and the insertion loss is relatively small.Finally,an intermediate frequency 3d B bandwidth of 13GHz(2-15GHz)is realized.When the local oscillator power is 0d B,the RF frequency is 27 GHz,and the local oscillator frequency is 21 GHz,the input 1d B compression point is-2.7d Bm;when the RF frequency is 23.5GHz-30 GHz,the conversion gain is-2?-0.7d B.Finally,in response to the needs of the new 5G millimeter wave communication chip,this article has implemented a high linearity wideband mixer through the improvement of the circuit.The mixer core still uses a passive double-balanced structure with good linearity and broadband performance.In order to achieve good linearity,the IF balun still uses a passive balun,and the IF buffer stage uses a broadband transimpedance amplifier with better linearity.In addition,peaking inductance is used,which not only resonates the parasitic capacitance of the TIA,improves the bandwidth performance,but also filters out high-frequency spurs and increases the harmonic suppression of the mixer.Finally,an input 1d B compression point greater than 2.2d Bm and a flatness of 0.2d B are achieved in the working frequency band,and the conversion gain is-3?-2d B.