Based On The Lte Base Station Power Amplifier Research And Design Of Analog Predistortion

Wireless mobile communication is getting widely used. The amount of informationpropagated becomes much more huge, the band resource becomes much more precious,the non-constant envelope and high peak-average power ratio affect seriously theperformance of mobile communication system. All these technique challenge meansthat high linearation is required for wireless mobile communication system. Thisdissertation focuses research on power amplifier’s linearity performance of LTE mobilebase station. Based on the requirement of LTE mobile base station power amplifier’slinearity, the APD is analyzed, simulated and designed. An improved APD circuit is putforward which can produce more accurate required pre-dictorion3rdinter-modulation(IM3) signal. The improved APD circuit contains two pairs of anti-parallel Schottkeydiodes. The pair of anti-parallel Schottkey diodes differences from conventional APD inimpedance adjustment. This improved APD circuit can be applied with the poweramplifier to get good linearation performance in more wide input amplitude. Theimproved APD circuit is fabricated and tested. The main work is as follows.1. The non-linearization of a power amplifier is studied. The non-linearity of a LTEbase station PA is analysed. In this dissertation, the LTE base station PA is aDoherty circuit in which amplifying device is Freescale MRF8P26090H. Asimulation model of this PA is constructed. Its pre-distortion IM3signal requiredis therefore calculated.2. The traditional APD circuit is analyzed and an improved APD is therefore putforward. The disadvantage of conventional APD and key parameters are put intoaccount. Simulation models for several conventional APD circuits areconstructed for studied. To solve the pre-distortion IM3signal narrow adjustablerange problem of conventional APD, a new pair anti-parallel Schottkey diodesconstruction is put forward, in which one of the two diodes is series connectedwith impedance. In this paper, two of this improved pair anti-parallel Schottkeydiodes are applied to generate accurate pre-distortion IM3signal. The simulatedresult shows that the IMD3suppression of the power amplifier can get more than 20dB improvement at46.3dBm (P1dB) output.3. Based on the simulated resulted, the improved APD is designed, fabricated. It istested with the Doherty amplifier. The tested results are as follows: the poweramplifier’s two IM3signals get16.3dB and14.3dB suppression improvementrespectively at43.4dBm output.All the work conducted in this dissertation has theoretical and engineeringreference value.