A Precise Harmonic Control Technique for High Efficiency Concurrent Dual-Band Continuous Class-F Power Amplifier

Zhenxing Yang,Zhiqiang Yu,Zhen Geng,Mingyu Li,Yi Jin,Yao Yao,Tian Li

doi:10.1109/access.2018.2870865

Abstract

In this paper, a design approach for a high-efficiency concurrent dual-band power amplifier (PA) with precise harmonic control up to third order is proposed. With the precise harmonic control approach, the high-efficiency performance of the PA can be improved at two arbitrary wide interval frequencies. Based on the inherent impedance matching flexibility of the continuous Class-F (CCF) operating mode, the design spaces of fundamental and harmonic impedances of the PA are largely expanded. The optimal impedances of a CCF PA mode at the internal current-generator (I-gen) plane and package plane are investigated, respectively, and a novel dual-band matching network topology is designed to simultaneously present required load impedances at the fundamental and harmonic impedances of both operation frequencies. First, a harmonic control network is designed to control the harmonic impedances precisely for CCF operation. Then, the fundamental impedances are synthesized using the real frequency technique. To verify the validity of proposed methodology, a dual-band CCF PA operating at 2.6 and 3.5 GHz is designed, fabricated, and measured. The measurement results show that the peak drain efficiency is 76.7% with an output power 42.4 dBm at the lower band and 72.8% with an output power 41.1 dBm at the upper band.

Highlights

The fast development of wireless communication systems and the roll-out of new standards require that the RF front can support multiple standards to meet the past and present demands of different industrial applications
It demonstrates that the proposed matching method is very effective for designing the matching network with precise harmonic control, which is useful for the design of high efficiency dual-band power amplifier (PA)
With the increment of output power from 30 dBm to 36 dBm, the drain efficiency (DE) gradually increases to 35.5%, while ACLR is between −31.2 dBc and −38 dBc at 2.6 GHz and the DE gradually increases to 38%, while ACLR is between −25.5 dBc and −35 dBc at 3.5 GHz

Summary

INTRODUCTION

The fast development of wireless communication systems and the roll-out of new standards require that the RF front can support multiple standards to meet the past and present demands of different industrial applications. As the short circuit condition at 2f1 is satisfied at plane P3 of Fig. 4, if the characteristic impedance ZT 4 is assumed to be a free design parameter, the electrical length θT 4 can be obtained as: θT 4. The second harmonic impedance of f2 at plane P5 is infinite as the fundamental matching network is designed with RFT, which mean that series open condition is satisfied. It should be noted that the characteristic impedances ZT 2, ZT 3, ZT 4, ZT 5, and ZT 6 are all free design parameters, which can give larger design spaces for harmonic control as well as fundamental matching These values can be selected in a large range, which can fit the physical constrains on the adopted technology or decrease the network size. FUNDAMENTAL MATCHING WITH RFT Once the harmonic tuning network is designed, the ABCDparameters of this network can be derived by applying a matrix formulation of cascaded two-port networks, which can be given as [AHi]

Ai Bi

Findings

CONCLUSION