Generation Mechanism for 3^<rd> Order Inter-Modulation Distortion in Harmonic Frequency Controlled Ultra-High Efficiency Amplifier

提出了f类高效微波放大器的电路合成方法，其中在设计中考虑了高达7^< >阶的高谐波频率。在f类微波放大器中，晶体管的负载阻抗在偶次谐波频率下为零，在奇次谐波频率下为无穷大。在异质结双极晶体管（HBT）中，由于基极-集电极电容等输出寄生电容的介入，使得晶体管的开路状态难以保持。此外，f类负载电路的电路损耗也会降低功率效率。在本项目中，利用ISE-TCAD二维器件模拟器，导出了f类放大器工作时HBT集电极的最佳掺杂密度。并介绍了tan δ=0.0023的低损耗树脂电路板，设计并制作了考虑7^< >次谐波频率的F类负载电路。制作的InGaP/GaAs HBT f类放大器电路工作在1.9 GHz，其PAE（功率附加效率）测量值为74.2%，集电极效率测量值为76.6%。在去嵌入电路损耗的情况下，PAE为78.7%，集电极效率达到81.2%。这些值是工作在2ghz左右的微波放大器的基准结果。在3^<rd>阶调制间失真的观点中，不仅要考虑基频，还要考虑谐波和次谐波频率，因为这些频率之间的频率混频现象对失真产生起着重要的作用。在FET f类放大器中，由于消除了通过偶次高谐波频率产生的机制，偶次高谐波频率的短路条件带来的畸变较小。但在HBT类f放大器中，由于基极对集电极电容较大，畸变产生机理较为复杂。指出了3^<rd>阶互调失真信号存在多矢量间的自补偿。从次谐波频率终止条件的角度出发，发现在偏置供电网络中短路滤波电路可以有效地降低双频和W-CDMA信号的畸变。少

Circuit synthesis methods for class-F high efficiency microwave amplifiers have been proposed, where up to 7^<th> order higher harmonic frequencies are taken into consideration in the design. In the class-F microwave amplifiers, load impedances for a transistor are zero at even order harmonic frequencies and those are infinity at odd order harmonic frequencies. Because of intervention of output parasitic capacitance such as base-collector capacitance in heterojunction bipolar transistors(HBT), the open circuit condition for the transistor is difficult to be retained. In addition, circuit losses in class-F load circuit degrade power efficiency also. In this project, using the ISE-TCAD two dimentional device simulator, optimum doping density for HBT collector has been derived for the class-F amplifier operation. And also introducing low loss resin circuit board with tan δ=0.0023, class F load circuit considering up to 7^<th> order harmonic frequencies were designed and fabricated in a di … More stributed circuit form. Fabricated InGaP/GaAs HBT class-F amplifier circuits operating at 1.9 GHz delivered 74.2% measured PAE(Power Added Efficiency) and 76.6% measured collector efficiency. In the case that circuit loss is de-embedded, the PAE is 78.7% and the collector efficiency reached 81.2%. These values are bench mark results in microwave amplifiers operating around 2 GHz.In a 3^<rd> order inter modulation distortion view point, not only a fundamental frequency, but also harmonic and sub-harmonic frequencies should be taken into account, since frequency mixing phenomena among these frequencies take important rolls for distortion generations. In FET class-F amplifier, short-circuited conditions for even order higher harmonic frequencies bring about less distortions, since generation mechanism via even order higher harmonic frequencies are deleted. However in the HBT class-F amplifiers, because of existence of large base to collector capacitance, the distortion generation mechanism are more complicated. It has been pointed out that self compensation among multi vectors for 3^<rd> order inter-modulation distortion signals occurs. In a view point of sub-harmonic frequency termination conditions, short circuited filtering circuits at bias supplying networks are found to be effective to reduce the distortions for both two tones and W-CDMA signals. Less