Research And Design Of High Linearity CMOS Mixer

As a nonlinear circuit,mixer is an indispensable component in modern transceivers.The ideal mixer is used as an ideal multiplier,and the two input signals are multiplied to achieve up-conversion or down-conversion.But in practical applications,not only because the input signal itself is not an ideal signal,but also mixer circuit itself has non-linearity,which reduces the quality of the output signal,making the mixer often unable to achieve good results in practical applications.And mixer is the front module of the receiver,it determines the performance of the receiver,so it is of great significance to study mixer.This thesis first introduces the research status of mixer,and then focuses on the Gilbert cell mixer,and analyzes and introduces its performance indicators(frequency conversion gain,noise figure,linearity,etc.).This thesis focuses on the study of down-conversion high linearity radio frequency(RF)mixers.The basic cell of mixer used in this thesis is the Gilbert cell,which is the most widely used mixer topology in modern communication systems.Using the SMIC 0.13μm CMOS process,a C-band down-converting active mixer was designed by using the derivative superposition method(DS),and analyzed and debugged to effectively improve the mixer Linearity.The work-ing voltage of the circuit is 1.5V.Simulation using Cadence software shows that the conversion gain of the circuit is 7.58dB,IPdB is-13.5dBm,IIP3 is-7dBm,the circuit power consumption is 16.05mW,and the noise figure is 10.7dB.By exploring the re-lationship between VGS,1a and IIP3,it can be seen that the linearity of the mixer is too sensitive to VGS,1a.Balun is a passive device often used in mixers.But in the actual circuit design,be-cause there is no ready-made balun in the process library for design,it needs the designer to design by ourselves.This makes the design process consume a lot of resources and time.And if you can discuss the size of balun,you can guide the design of the actual balun.First,a brief introduction to balun.Introduced the Marchand balun,and ana-lyzed the principle of single-ended to differential signal.After that,the performance index and research status of balun were briefly introduced.Then introduce the eight baluns of different specifications designed in this design,and use ADS to simulate the electromagnetic field,and analyze the impact of different sizes on the performance of the balun according to the simulation results.