Research On CMOS Linear RF Power Amlifier

With the development of mobile communication systmen,it requires the radiofrquency(RF)front—end module(FEM)with high performance,low cost and widebandwidth．Due to the low cost of CMOS(Complementary Metal OxideSemiconductor)process and easy implementation on small RF signal devices andlogic control circuits,it is recognized as one of the promising single chip FEMsolutions．However,currently,it is still difficult to implement the reliable RF poweramplifier(PA)because CMOS transistor has the low breakdown volatge,conductivesubstrate and no vias．In this research,the configuration of CMOS PA andlinearization techniques are studied based on the charisteritcs of CMOS process,andthe fully—integrated CMOS PAs are implemented．It has big sense on implementationsof single chip CMOS FEM finally．Firstly,the structure of power cell for large signal operation and its analyzedmodel are proposed．The optimum single finger width and total width of power cellare concluded based on the optimization,and they are vwerificated with standard0．1 8 um CMOS process．The measured results reveal that the structure has the lowcost and confirms well with the proposed model,and is also scalable．This workprovides solide base for high power PA design．Secondly,the on—chip comnpact and low loss transformer is proposed with theeven mode and odd mode theory．The bandwidth and loss of transformer are analyzedwith the even mode and odd mode theory for difl~neratial confignaration of CMOSPA,the method that adding lumped capacitors at the input and output is proposed toreduce the loss and size．The analysis is verificated with the fabrication．Thirdly,based on the proposed power cell and transformer,the wideband CMOSPA is designed as the background of m—WiMAX《Mobile Worldwide Interoperabmtyfor Microwave Access)．The wide bandwidth is obtained by absorbing the parasiticparameters of output matching circuit into the load impedance matching to reduce thefrequency response．The fully—integrated PA is implemented in TSMC 0．1 8 umCMOS process．All of the input and output matching components are integated onchip,and the total size of chip is only 1．2 mm×2 mm．The measurment reveals that ithas 1 GHz bandwidth Fourthly,The lineairty of CMOS PA is enhanced with the analog pre—distortiontechnique．The strong nonlinear transconductance of CMOS transistor and its thordharmonic are analyzed．The third harmonics genertaed by power stage and driverstage are canclled within the specific output power,thus the lineairty is enhanced．The theoretical analysis is verificated with TSMC 0．18 um CMOS process．Themeasurements reveal that the m—WiMAX spectrum can be improved by 8 dB．Finally．the 2．5一GHz and 3．5-GHz dual band CMOS PA is designed with thecharacteristic that output matching capacitor has big impacts on operation frequencyband．The dual band matching is achieved by switching capacitor values；theinter—stage and input matching are also optimized to guarantee the performance．Theanalysis is verificated with Dongbu 0．13um CMOS process．The measurementsreveal that the PA can achieve 29 dBm and 28．5 dBm at 2．5 GHz and 3．5 GHz．respectively,and confirms well with the simulation．his work utilized the current standard CMOS process design the high powerfully—integrated CMOS PA,and studies deeeply on high linearity,wide bandwidthand chip size reduction．The challenges are overcome due to the restrictions ofCMOS process and it has big sense on implementation of high performance and lowcost RF CMoS FEM．...