Research And Design Of A Ultra-wideband Low Noise Amplifier And A Mixer In SiGe BiCMOS

As the fast development of the wireless communication technology,wideband wireless communication system is becoming one of the main high data-rate communications.In particular,the Software Defined Radio?SDR?which could compatible diverse standards.The SDR avoids the dependence of hardware,makes the different frequency band,the different modulation,the different standards share the hardware.That shows its broad prospects in the future communications.Radio Frequency?RF?front-end technology,located in the forefront of receiver system,is a key technology of Software Defined Radio,and its performance is decisive to the performance of communication channel.To design a front-end chip with a good performance,this paper analyses the merits and drawbacks of various architectures in detail,and puts forward the whole solution for SDR according to its frequency band.Signal is amplified by UWB-LNA,divided into different signals by active Balun,and down converted to 100MHz by active Mixer finally.According to this solution,the author researches the key technology of UWB-LNA,Balun and Mixer,and completes the design of them based on 0.18?m Jazz Semiconductor SBC-18 BiCMOS process technology in cadence.In the front-end,UWB-LNA is based on the cascode configuration with resistive feedback.A LC matching network and the feedback resistor are used to achieve wideband input-impedance matching.A emitter follower is used to achieve wideband output matching.Active balun employs a cascode different circuit to eliminate miller effect.At the same time,to reduce amplitude imbalance and phase imbalance,an active inductance is used as the load,a smile size BJT is used as current source.The active mixer has been designed based on Gilbert cell architecture and uses a current injection method for improving the gain and linearity.Bipolar transistors are used as switch to decrease the 1/f noise.This mixer down converts RF signals to a fixed IF of 100MHz to simple the design of IF filter in the next stage.This paper detailedly introduces the design process and idea of RFIC,and makes theoretical analysis,circuit simulation of each module.After repeated optimization of layout and schematic,the author got the post-simulation by calibre:in 1-8GHz band,the conversion gain of the front-end chip is from 43.3dB to 45.4dB,flatness is less than 2.1dB,and its noise figure is below to 5.67dB.The post-simulation results of UWB-LNA show that the power gain S₂₁ is 21.3 to 23dB,flatness is less than 1.8dB,the noise figure is under2.4dB,both input matching S₁₁ and output matching S₂₂ are less than-10dB;inverted isolation is less than-47.7dB,power consumption is less than 23mW.The active balun's post-simulation results show that the power gain is 6.2±0.5dB,the gain's mismatch is less than 73mdB,and the phase difference of the two balanced ports with a good output matching is less than 0.8deg,the power consumption is less than 5mW.The broadband active mixer's conversion gain is from 11.3 to 12.2dB with a flatness less than 1dB,and the IIP3 point referred to input is-7dBm,the RF return-loss is well below-10dB,the isolation between each port is less than-60dB,while the NF is about 11.8dB,the DC power consumption of the mixer is only 10mW.All characteristics of each module and the whole chip meet the design objective.And the simulation result is the same as the theoretical analysis.