Analytical Design Methodology for Generic Doherty Amplifier Architectures Using Three-Port Input/Output Networks

Abstract

In this paper, a new Doherty amplifier architecture along with an analytical based design methodology is proposed. The proposed architecture uses novel three-port network as the output matching/combining network (OMCN). The three-port OMCN performs the power combining for any arbitrary output power ratios from the two transistors of the Doherty amplifier. It also performs the impedance matching from any arbitrary complex load impedance to the optimum impedances for both transistors at peak output power. Commonly in Doherty amplifiers, an optimum performance at peak power and a sub-optimum performance at power back-off are often obtained. Using the proposed output network, optimum performance can be reached at power back-off, as well as at peak power. Another three-port network is proposed for input matching/dividing network (IMDN) at the input of the proposed Doherty amplifier. The three-port IMDN is designed to perform the power division with any arbitrary division ratio, adjust the arbitrary phase difference between the input signals to the two transistors, and provide the impedance matching from any arbitrary complex source impedance to the optimal source impedances for the two transistors. To verify the provided theory, two prototype amplifiers are designed and tested. A 12-W amplifier is designed for a 50source and load impedances at 1 GHz. Another 12-W amplifier is designed at 1 GHz for complex source and load impedances. Both amplifiers have efficiency of higher than 50% at 7-dB output power range.Index Terms-Back-off, Doherty amplifier, efficiency, peak-toaverage power ratio (PAPR), three-port network.

Design of Wideband Power Amplifier in 130nm CMOS for LTE Applications

“…With growing number of frequency bands in mobile communication to meet the demands of data rate, power amplifiers (PA) arerequired to operate at entire wide range of frequencies in mobile communication systems along with meeting the requirement of PAs linearity, adjacent channel leakage ratio (ACLR), error vector magnitude (EVM) and output power. However, existing multiple PAs operating for each frequency band would increase the complexity and cost of wireless communication systems especially when they are required to support more frequency bands [1]- [3]. In addition, PAs' distortions caused by their nonlinear behaviour, usually degrades their performance when high power and high efficiency is considered [1]- [3].…”

“…However, existing multiple PAs operating for each frequency band would increase the complexity and cost of wireless communication systems especially when they are required to support more frequency bands [1]- [3]. In addition, PAs' distortions caused by their nonlinear behaviour, usually degrades their performance when high power and high efficiency is considered [1]- [3]. Therefore, removal of distortions caused by nonlinear behaviour of PA in diodes and transistors is crucial [1]- [3].In order to ensure broad coverage of frequencies by PA, a multimode multiband feature is required to be incorporated in its design to meet the communication standards of current and future mobile communication systems [1]- [4].…”

“…In addition, PAs' distortions caused by their nonlinear behaviour, usually degrades their performance when high power and high efficiency is considered [1]- [3]. Therefore, removal of distortions caused by nonlinear behaviour of PA in diodes and transistors is crucial [1]- [3].In order to ensure broad coverage of frequencies by PA, a multimode multiband feature is required to be incorporated in its design to meet the communication standards of current and future mobile communication systems [1]- [4]. High output power and high efficiency with minimum distortions are achieved by incorporating a matching network in PA design.…”

“…The presence of matching network in PA design provides a maximized power transferred between source and load [1] [3] [4]. Power amplifier with optimized matching network ensures reduction of nonlinear signal generated by the PA.…”

Effect of input phase mismatch in Doherty power amplifiers

“…Comprehensive analyses have been done for Doherty power amplifiers starting from early 2000s [9,10,11,12,13]. The full load matching circuits is demonstrated by using offset lines at the output of the matching circuits for proper Doherty operation at both low and high power region [14].…”