仿真分析了由于高功率放大器(High Power Amplifier,HPA)的非线性失真对OFDM信号造成的影响.设计了基于清华大学DMB-T高清晰度数字电视标准的SSPA(Solid State Power Amplifier)3W功放,利用了多项式拟合及FPGA技术.考虑到曲线拟合误差和HPA的特性,采用了分段拟合,硬件实现了SSPA的预失真,可将带外功率失真降低约10dB左右,在很大程度上抑制了带外及带内失真。
In this paper, we analyze the effects of HPA nonlinear distortion on the OFDM signals. Based on the SSPA 3-watt power amplifier of DMB-T system in Tsinghua University, SSPA pre-distortion is successfully implemented with hardware by using the segmental polynomial fitting and FPGA techniques. About 10dB PSD reduction can be acquired, suppressing the in-band and out-of band noises to a large extent.