微波電路期中報告 論文研討 : Experimental Design Method for GHz-Band High- Efficiency Power Amplifiers Based on MHz-Band Active Harmonics Load-Pull Technique Ryo Ishikawa, Yoichiro Takayama, Kazuhiko Honjo Proceedings of APMC 2012, Kaohsiung, Taiwan, Dec. 4-7, 2012 報告人 : 碩研電子一甲 MA 柯慶宏 Southern Taiwan University Department of Electronic Engineering

Introduction 1 Proceedings of APMC 2012, Kaohsiung, Taiwan, Dec. 4-7, 2012 Ryo Ishikawa, Yoichiro Takayama, Kazuhiko Honjo Fig. 1 (a) shows the load configuration of a high-efficiency amplifier. A transistor can be modeled with parasitic elements and with a nonlinear current source that does not relate to a frequency. The reactive parasitics can be ignored at the MHz-band. Then, the optimum load impedance for a transistor without reactive parasitics can be estimated in the MHz-band by using a simple active load-pull system, as shown in Fig. 1 (b). Therefore, in the GHz-band, the optimum impedance outside the transistor can also be estimated by considering the reactive parasitics.

MHZ-BAND ACTIVE LOAD-PULL SYSTEM 2 Proceedings of APMC 2012, Kaohsiung, Taiwan, Dec. 4-7, 2012 Ryo Ishikawa, Yoichiro Takayama, Kazuhiko Honjo Fig. 1. Principle of optimum load impedance estimation for high-efficiency power amplifiers. (a) Circuit configuration of the high-efficiency amplifier. (b) Active load-pull system including harmonics at a MHz band to obtain ZLopt.

3 Proceedings of APMC 2012, Kaohsiung, Taiwan, Dec. 4-7, 2012 Ryo Ishikawa, Yoichiro Takayama, Kazuhiko Honjo

4 Proceedings of APMC 2012, Kaohsiung, Taiwan, Dec. 4-7, 2012 Ryo Ishikawa, Yoichiro Takayama, Kazuhiko Honjo Fig. 3. Measured voltage and current waveforms at the HEMT and load impedance conditions for each operation. (a) A class-F operation. (b) A capacitive element is added at the fundamental frequency. (c) An inductiveelement is added at the fundamental frequency.

5 Proceedings of APMC 2012, Kaohsiung, Taiwan, Dec. 4-7, 2012 Ryo Ishikawa, Yoichiro Takayama, Kazuhiko Honjo REACTIVE PARASITICS ESTIMATION Fig. 4. (a) Schematic drawing of circuit-impedance estimation. (b) Measured susceptance at the output side of the HEMT and target impedance for a 1.9 GHz operation.

6 GHZ-BAND LOAD CIRCUIT DESIGN Proceedings of APMC 2012, Kaohsiung, Taiwan, Dec. 4-7, 2012 Ryo Ishikawa, Yoichiro Takayama, Kazuhiko Honjo Fig. 5. Fabricated amplifier designed at 1.9 GHz Fig. 6. EM simulated (left) and measured (right) circuit impedance characteristics for the load circuit

7 Proceedings of APMC 2012, Kaohsiung, Taiwan, Dec. 4-7, 2012 Ryo Ishikawa, Yoichiro Takayama, Kazuhiko Honjo Fig. 7. Measured waveforms and load impedance in the 20MHz active load-pull system for the measured impedance at 1.88 GHz Fig. 8. Measured input-output power response and efficiency characteristics

CONCLUSION 8 An experimental design method for GHz-band highefficiency power amplifiers based on a MHz-band active loadpull technique that includes harmonics tuning was introduced. Using this method, a load circuit design depending on the specific properties of the transistor can be achieved. For an InGaAs/GaAs HEMT, a load circuit at 1.9 GHz has been designed and fabricated based on a 20-MHz-band active loadpull evaluation, by taking parasitic elements into consideration.. A maximum drain efficiency of 77% was obtained at 1.88 GHz, which is very close to the design prediction. Proceedings of APMC 2012, Kaohsiung, Taiwan, Dec. 4-7, 2012 Ryo Ishikawa, Yoichiro Takayama, Kazuhiko Honjo

9 Experience 關於這篇作者所提出的一個實驗的設計方法，為 5GHz 頻帶高 效率功率放大器在 MHzband 有源負載拉移技術，包括諧波調 整。 其實看到後面還是看不懂他們設計出來的這個方法能應用在 什麼地方。