The Linc Transmitter Modulation Part Of The Hardware Design And Distortion Analysis

Based on the National Hi-Tech Research and Development Program (863), this project studies a novel high efficiency and linearity front-end of RF transmitter. LINC(Linear Amplification With Nonlinear Components)is a kind of broadband high efficiency and high linearity technologies. Due to its 100% efficiency theoretically and high linearity, it becomes one of the most potential transmitter techniques. However, it has demand to amplitude and phase consistency of two roads, which made generic a number of problems in project realizing.An in-depth research on parts of the transmitter front-end has been done in this dissertation. When the quadrature modulator is working in a high frequency, amplitude and phase is difficult to match each other exactly, plus the two-way local oscillator signal distortion, making modulation part have an obvious effect to system. This paper firstly studies the effect made by the inherent linear distortion of quadrature modulator to the LINC system, then analysis focus on the effect of system made by phase noise of local oscillator and two-way divided range of local oscillator amplitude and phase distortion. According to the analysis results, it showed that the LINC system is very sensitive to gain and phase imbalances of two-way signals, which made very high demand to the hardware design, as a result, consistent symmetry of two-way should achieved to reduce the distortion of the system caused by hardware impact when making hardware design.Task and contributions in this subject are as follows:1,ACPR and EVM that were influenced by Carrier leakage, amplitude and phase distortion, the local oscillator signal phase noise as well as amplitude and phase distortion in the orthogonal modulator have been analyzed.2,Various parts of LINC transmitter modulation system such as couplers, filters, modulators, etc have been designed;3,After designing various parts of the circuit schematic, design, production and debugging of four-layer PCB circuit board have been completed which followed the principles of RF circuit layout. 4,Main contribution of this paper is that a systematically analysis is made to the distortion caused by the modulation to the indexes of the system, and completed the modulation part of the hardware design, which is a very good guide to follow-up study.