Ka波段高精度模拟预失真线性化器

模拟预失真技术是改善行波管放大器非线性失真的一种有效方法,但补偿精度较低的缺点是制约其进一步发展的关键因素。增益相位独立调节技术和补偿曲线形状调节技术是提升模拟预失真补偿精度的重要技术。提出了一种适用于Ka波段行波管放大器的高精度模拟预失真器,该预失真器采用双路矢量合成式结构,在29~31 GHz 范围内,通过调节二极管偏置电压可以同时实现补偿曲线形状调节和增益相位扩张量独立调节,有效提升了补偿精度。与行波管放大器的联合测试结果表明,在30 GHz 时,该预失真器可以将行波管放大器的增益压缩从5.3 dB 减小到1.2 dB,相位偏移从62°减小到6.5°。线性化后的行波管放大器的非线性失真明显降低,在输出功率回退5 dB 时,三阶互调系数提高了9.3 dB。

Ka-Band Analog Predistortion Linearizer with High Accuracy

Analog predistortion is an effective way to compensate the amplitude and phase distortion generated by traveling wave tube amplifies(TWTA). However, low adjustment accuracy is a deadly disadvantage restricting its further development. Independently amplitude modulation to amplitude modulation (AM/ AM) and amplitude modulation to phase modulation (AM/ PM) control is an important technique to raise the accuracy of analog predistortion and so is shape control. A Ka-band predistortion linearizer with high adjustment accuracy is proposed in this paper. From 29GHz to 31GHz, The linearizer based on vector synthesis structure can realize both independently AM/ AM and AM/ PM control and shape control by adjusting the bias voltages of diodes. The test results show improvements in linearity are achieved. The AM/ AM and AM/ PM characteristics of TWTA are improved from 5.3 dB and 62° to 1.2 dB and 6.5° by the predistortion linearizer. The third order carrier-to-intermodulation (C/IM3) is improved 9.3 dB at -5 dB output back-off (OBO).