Research On Key Technologies Of Monolithic Pre-distortion Linearizer

Wideband technology has been widely used in electronic warfare and radar communication.As the key component of the transmitter,the power amplifier needs to combine linearity and output power.For the linearization of wideband power amplifiers in communication systems,analog pre-distortion technology is competent and has superior performance.Currently,the bandwidth of domestic linearizers is still narrow and mainly used in satellite communication.On the other hand,the implementation of predistortion device in the form of monolithic microwave integrated circuit(MMIC)has the advantages of high integration and small size,which is more suitable for mobile warfare.In order to solve the current challenges of wideband design,flatness,and strong correlation of amplitude and phase characteristics of linearizers,this thesis carries out a study on the key technology of monolithic pre-distortion linearizers.The research content and innovation points are summarized as follows.A common-source FET two-way structure is proposed for reducing the bandwidth of the conventional pre-distortion structure.This structure is based on the principle of vector synthesis,which reduces the correlation between the output signal amplitude and phase characteristics.Based on this,a 2～6GHz wideband linearizer chip is designed using0.25 um Ga N HEMT process.The measured results show that the chip has 10.34～12.43 d B of gain expansion,21.3～26.8°of phase compression,≤1.90 d B of gain flatness in the band,and can achieve 6.21 d B of independent adjustment range of amplitude expansion,with a chip area of 1100um×1800um.A 0.25 um Ga As p HEMT process is used to design a 6～18GHz wideband linearizer chip.In order to simplify the pre-distortion circuit structure and reduce the chip size,a common-gate FET transfer structure is used with a chip area of 850um×750um.The measured results show that the chip has 6.2～9.4d B of gain expansion,39.0～70.1°of phase compression,≤2.82 d B of in-band gain flatness,and can achieve an independent adjustment range of 35°of phase compression.In order to drive the developed linearizer chip and explore the improvement of the nonlinear distortion of the power amplifier by the chip,the drive circuits are developed and tested with cascading the target power amplifier under single-tone and two-tone signal excitation.The test results show that the 2～6GHz linearizer chip improves the amplifier P1 d B output power by 5.32～7.69 d B in the frequency band;at the saturation power back of 3d B and 5d B,the linearizer chip improves the IMD3 of the amplifier by11.50～14.30 d B and 12.56～16.62 d B.Similarly,the 6～18GHz linearizer chip improves the amplifier P1 d B output power by 1.11～1.78 d B in the frequency band;at the saturation power back of 3d B and 5d B,the linearizer chip improves the IMD3 of the amplifier by6.25～12.61 d B and 8.33～13.82 d B.