Analysis And Design Of RF Power Amplifiers On Linearization And Stabilization

The radio-frequency (RF) power amplifier (PA) is one of the key components of transceiver front-ends for modern wireless communication systems, RADAR, and electronic countermeasure. Its stability is necessary for system working and its linearity directly affects the performance of non-constant envelope modulation system. Thus the linearization and stabilization of RF PAs are always the hotspot and difficulty of RF electronic research. The linearity and stability of RF PAs for wireless communication are analyzed in this dissertation. The principal contributions of this dissertation include:The envelope elimination and restoration (EER) technique has been widely applied to improve the efficiency and the linearity of RF PAs simultaneously. A new method is proposed to analyze the intermodulation distortion (IMD) of RF PAs with EER. A general simplified model for IMD is founded which varies with the bandwidth of envelope path and the differential delay between envelope and phase signals, and overcomes the limitation of Raab's model which can only solve such two specific instances as zero differential delay and infinite bandwidth of envelope path. A contour map derived from the general model in this dissertation is helpful for the designers to choose circuit parameters quickly and accurately.A novel adaptive delay-control method, implemented in the baseband, is presented to improve the linearity of RF PAs with EER. This method can be applied to the linearization of wideband PAs and makes the RF PAs easy to meet the spectral mask specification of IEEE 802.11b wireless communication systems with 11MHz-bandwith effectively. The relationship between the compensated delay and the bandwidth of envelope signal and envelope path comes out by the analysis for loop model. Based on deep sub-micron CMOS technology, the stability of PA operated beyond large signal is analyzed by system identification method. The sub-harmonic oscillation is eliminated by feedback network which removes the unstable poles of PA.The PAs are fabricated with and without stabilization circuit respectively. Based on the test results, this dissertation analyzes the effects on stability due to circuit parameter fluctuation, especially on potential sub-harmonic oscillation of PAs in deep sub-micron technology.