Research On New High Efficiency Outphasing RF Power Amplifier

As the most energy-consuming part of the RF transmitter system,the RF power amplifier basically determines the overall performance of the transmitter.Outphasing power amplifier,also known as out-of-phase power amplifier,due to its outstanding efficiency in deep saturation,insensitivity to amplitude information,and good digital compatibility,etc.,Outphasing power amplifiers will have promising future.Therefore,this article focuses on the research of high-efficiency wideband Outphasing power amplifiers.First of all,based on the traditional Chireix Outphasing power amplifier structure,this paper completes the complete design method and design theory of Outphasing power amplifier.On this basis,in order to solve the problem of increasing the circuit components and circuit size due to the need for additional output matching,this paper proposes a compact Chireix Outohasing power amplifier design method,and at the same time verifies the design.The results show that when the signal output power is backed by 6d B,the drain efficiency is 63.5%,which is nearly 10% higher than the traditional Doherty type.Then,this paper focuses on the bandwidth improvement method of Outphasing power amplifier.The traditional Outphasing PA needs to meet the strict phase control and impedance modulation relationship,and the traditional matching network composed of microstrip lines is difficult to achieve large bandwidth operation due to the dispersion effect.In this paper,based on the classical Chireix Outphasing theory,special circuit structures such as T-type and Pi-type are used to realize impedance transformation lines and reactance compensation structures with different characteristic impedances and electrical lengths in dual-band.By replacing the λ/4 impedance conversion line and the imaginary compensation network under the original single-band,a high-efficiency Outphasing amplifier supporting both 2.6 GHz and 3.5 GHz dual-band operation is finally realized.The saturation efficiencies were 71% and 64%,respectively.And the drain efficiencies were 58.4% and 50.1%,respectively,when the signal output power was 6 d B back.The design method is the only research result of the dual-band Outphasing report that is currently reported.Finally,this paper develops and improves the design of dual-band Outphasing power amplifier based on non-commensurate transmissions lines structure,gives detailed and complete design theory and designs a dual-band Outphasing circuit based on non-commensurate transmissions lines.The non-commensurate transmissions lines circuit eliminates the imaginary part compensation compared to the conventional Chireix circuit,and the circuit structure is further simplified.The test results show that the saturated drain efficiencies are 74.5% and 63.5% in the 2.6 GHz and 3.5 GHz bands,respectively,and the drain efficiencies are 63.8% and 53%,respectively,when the output power is backed off by 6 d B.This solution not only completely discusses the new dual-band design method,but also greatly improves the size and performance compared to the Chireix Outphasing structure.