CMOS power amplifiers for WLAN and 5G & B5G communications

Abstract

In this paper, the nonlinearity of a power amplifier designed using a CMOS process is improved and a study on a method for designing a high performance power amplifier is presented. In addition, this paper describes the design method of in-band full-duplexing (IBFD) power amplifier to be used in future wireless communication. To verify this, vari-ous techniques were applied to 2.4 GHz WLAN linear power amplifier, mmWave linear power amplifier, and mmWave IBFD power amplifier. First, we proposed a common-gate (CG) combine structure consisting of class-AB non-linear main CG power amplifier and class-C auxiliary CG power amplifier. The opposite AM-AM and AM-PM characteristics of the two power amplifiers are simultaneously compensated to dramatically improve the linearity. In addition, the CG combine structure enables high performance power amplifiers with high P1dB and linear efficiency values. Next, linearization techniques of various mmWave power amplifiers are proposed. These methods include dynamic feedback control, neutralized capacitor, 2nd harmonic termination, and restricted adaptive bias control. The dynamic feedback control circuit extracts the envelope signal of the input signal through the detector and delivers it to the feedback circuit. This allows feedback of the power amplifier to be adjusted according to the envelope of the input signal. The restricted adaptive bias control circuit is a technique for adjusting the bias of a transistor using an envelope signal extracted through an envelope detector. In particular, we proposed a method to make the design more convenient by using series resistors. Both of these methods improve AM-AM and AM-PM and improve power gain and efficiency to create a high-linearity, high-performance power amplifier. Neutralized capacitors can improve AM-AM through positive feedback and improve the AM-PM by eliminating the effects of common-source (CS) parasitic capacitors. It also has the effect of increasing power gain and thereby increasing efficiency. Finally, 2nd harmonic termination reduces the asymmetry of IMD3 and affects the im-provement of IMD3 as a whole. Finally, we proposed an in-band full-duplexing power amplifier to be used in next-generation wireless communication technologies. The in-band full-duplexing power am-plifier can secure the isolation between the transmitter and the receiver using the hybrid transformer structure, thereby enabling the operation of the transmitter and the receiver in the same frequency band. The proposed method is applied to the output impedance match-ing transformer of the power amplifier to improve the problem of chip size and front-end integration of the circuit, and to overcome the disadvantage of the intrinsic 3dB power loss of the hybrid transformer.