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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。
The simulation of predistortion technology is an effective method to improve the nonlinear distortion of TWT. However, the disadvantage of low compensation accuracy is the key factor that restricts its further development. Gain phase independent adjustment technology and compensation curve shape adjustment technology is to improve simulation accuracy of pre-distortion compensation important technology. A high-precision analog predistorter for a traveling wave tube amplifier in the Ka-band is proposed. The predistorter uses a two-way vector synthesis structure and can be compensated simultaneously by adjusting the diode bias voltage in the range of 29-31 GHz Curve shape adjustment and gain phase expansion independently adjusted, effectively improving the compensation accuracy. The joint test with the TWT amplifier shows that at 30 GHz, the predistorter reduces the gain compression of the TWT from 5.3 dB to 1.2 dB and the phase offset from 62 ° to 6.5 °. The nonlinear distortion of the linearized TWT amplifier is significantly reduced. The third-order intermodulation coefficient is increased by 9.3 dB when the output power is retracted by 5 dB.