Research On Millimeter-wave Predistortion Linearization Technology

The wireless communication system possessing the characteristics of multi-user, large capacity and high transmission rate is more and more popular, which makes millimeter-wave communication system within broader working band and larger data capacity become a key. Broadband multi-carrier complex digital modulation technique has very high request for linearity, especially the millimeter-wave power amplifier in the transmitter, and this efficient modulation technology is usually adopted in current millimeter-wave communication system. Power amplifiers in the last stage of wireless communication system often work with strongly nonlinear operation in order to obtain high power and reduce the cost of the system. When power amplifiers have enough output power and high efficiency, we should make use of some compensation technologies to improve the linearity of them.This thesis has studied in depth the analog predistortion linearization technology which can compensate the nonlinear distortions of the high power amplifiers, especially the Ka-band power amplifiers(PAs). The main research contents of this thesis are as follows:This thesis have put forward an amplitude-phase tunable analog predistortion linearizer for use of solid state power amplifiers(SSPAs) and travelling wave tube amplifiers(TWTAs) based on the method of vector synthesis. The experimental results verify that this predistortion linearizer is well adjustable, and it can improve the linearity of SSPAs and TWTAs at the same time.Based on the reflection characteristics of the parallel Schottky barrier diode and the method of vector synthesis, we have proposed a dual-type analog predistortion linearizer. The predistortion linearizer possesses nice performance of predistortion ability and VSWR. It can provide 8dB magnitude expansion and 42° phase compression.In the final of this thesis, we have developed the Ka-band SSPA linearization power driver module on the basis of the millimeter-wave dual-type analog predistortion linearizer. The experimental results show that its magnitude expansion is more than 9dB, and phase compression is more than 38° in 29~31GHz when the input power dynamic range is 20 dB. Two-tone test results signify that the linearization power driver module can improved the IMD3 by 10dB(the best result is 25.02dB) at –7dB IBO in 29~31GHz. The linearization power driver module has nice performance of predistortion ability, and satisfies the design target.