The Research Of 4G Communication Multimode Multiband Power Amplifier

From only voice functions in the first generation of mobile phones,the cellphone now can make online video.With 4G today,the increasing demand for wireless communications,technology is also constantly evolving.In order to meet the demands of higher data transmission rate,in 4G communication standards,more complex OFDM technology is used to reach downlink data rates of150 Mbps and uplink 50 Mbps.OFDM is a multi carrier modulation technology.Though the data speed is enhanced by the increased carrier quantity,the peak power is also increased by multi carrier overlapping.The increasing peak power put a higher requirements on the linearity of power amplifier.GaAs HBT process was adopted in this design.Bandwidth of the power amplifier covered 2.3GHz to 2.69 GHz which contains FDD-LTE Band7,TDD LTE Band38,Band40,Ban41.A variety of techniques was adopted in the design to solve the following key issues in power amplifier design:(1)To overcome the inadequate gain caused by the high frequency parasitic effect,three stgage structure was adopted in the power amplifier;(2)Active bias circuit was used to compensate the nonlinearity caused by the increase of power and temperature;(3)Band-pass structure in the matching circuit was used to improve restraint of harmonic and power leakage beyond the bandwidth.;(4)second and third harmonic trap was add respectively output of 2-stage and3nd-Stage to improve the power added efficiency(PAE)and linearity;(5)In layout design,"fishbone" structure made uniform current distribution,which avoiding the overheating caused by uneven distribution of current.Finally,WCDMA R99 signal and LTE QPQK-10 MHZ-12-RB signals are used to test the performance of the power amplifier under different modulation signal.The measurement results show that the power amplifier,in 2.3 GHz to 2.69 GHz range,got 31dB-33 dB small signal gain and more than 33%PAE.The linearity under R99 signal was got ACLR-5 MHz<-40dBc@28dBm and ACLR-10 MHz<-56dBc@28dBm.When the power amplifier was tested under QPSK-10MHz-12 RB signal,the results shown that E-UTRA<-33dBc@28dBm,UTRA-ACLR1<-33dBc@28dBm,UTRA-ACLR2<-56dBc@28dBm.