一种射频功率放大器模拟预失真器研究

MRI RFPA analog predistorter research

根据模拟预失真器的基本原理和实现方法,设计出一种基于可调增益及其相位模拟预失真算法,并根据该算法,设计了基于DAC(Data Analog Convert)、FPGA(Field Programmable Gate Array)的硬件预失真器,然后对该电路进行制版、测试,得出该失真器的矫正能力。最后将该预失真器结合射频功率放大器进行系统测试,实现了在输入动态范围为30d B、工作频率为64MHZ条件下,AM/AM增益线性度改善了3.2d B,AM/PM相位线性度改善了6度。结果表明,该预失真器件具有一定的灵活性和矫正能力,可用于医疗1.5T核磁共振的射频功率放大器系统中。

Analog Pre-distorter is analyzed by principle of pre-distorter,and an analog pre-distorter algorithm is designed based on the principle of adjustable gain and its phase. According to the proposed algorithm,a control circuit based on DAC( Data Analog Convert、FPGA( Field Programmable Gate Array) is design and realized. The analog predistorter has been tested with RFPA and achieve gain linearity( AM / AM) improve 3. 2d B and phase linearity( AM /PM) also improve 6°,on the condition 30 d B dynamic range and frequency is 64 MHZ. This pre- distorter could be used in 1. 5T MRI RFPA( Radio Frequency Power Amplifier Magnet Resonator Imaging) system.