以微波帶通放大器實現高整合度射頻前端收發系統

梁廷維(Ting-wei Liang)

指導教授 ： 林祐生

國立中央大學/資訊電機學院/電機工程學系/碩士(2014年)

摘要

本論文研究主軸為帶通濾波器與放大器之整合，並以此實現高整合度射頻前端收發系統。首先為微波帶通功率放大器的研製，係整合微帶線帶通濾波器於功率放大器設計，並嵌入二極體於濾波器設計之中作為射頻開關，達到元件的多功能化，並縮小發射端電路面積，及提供良好的諧波抑制效果，亦能提高射頻前端的系統整合度。再來將帶通功率放大器與接收端之單端轉平衡帶通低雜訊放大器整合，完成同時具有收發切換開關、收發帶通濾波器、功率放大器、低雜訊放大器與平衡至非平衡轉換器之高整合度射頻前端收發系統。此系統接收頻帶為1.93 GHz到2.07 GHz，有11.5 dB以上的增益，大於10.2 dB的輸入與輸出反射損耗，低於2.9 dB的雜訊指數，平衡輸出之震幅差小於0.7 dB，相位差小於2.3度。系統發射頻率為2.2 GHz到2.3 GHz，於中心頻率2.25 GHz有8.2 dB的增益，21 dB的輸入反射損耗，15.2 dB的輸出反射損耗，於1 dB增益壓縮點時有25.8 dBm的輸出功率，38.1%的功率增加效率，三階輸出截斷點則為38.3 dBm。接收發射兩路皆整合了帶通濾波器，因此具有高頻率選擇度與良好的止帶抑制效果，另外在發射端諧波抑制方面，二次至五次諧波之輸出功率於1 dB增益壓縮點時，皆有-49.4 dBc以上的抑制效果。 針對上述高整合度收發系統架構，本研究提出簡潔的設計流程與設計公式，並於基板上實作驗證其可行性，而未來可以此設計理念，將其實現於積體電路製程，進一步縮小電路面積，提升此技術之競爭力。

關鍵字

微波 ； 射頻 ； 功率放大器 ； 低雜訊放大器 ； 濾波器 ； 收發機

並列摘要

This study investigates the systematic method in designing a highly-integrated RF front-end system based on the integration of bandpass filter and amplifier. Firstly, the design of a bandpass power amplifier is presented. It is achieved by integrating a coupled-line bandpass filter with a power amplifier, and a diode is also embedded in the filter structure to realize the RF switch. Then the proposed bandpass power amplifier is integrated with a single-to-balanced bandpass low-noise amplifier to achieve a highly integrated RF frontend system including single-pole-double-throw T/R-switch, bandpass filters for Tx/Rx, power amplifier, low noise amplifier, and balun. The receiver is design for 1.93 GHz to 2.07 GHz operation. The measured small-signal gain is more than 11.5 dB, the input/output return loss is better than 10 dB, the noise figure less than 2.9 dB, and good balance performance with 0.7 dB maximum amplitude imbalance and 2.3 degree maximum phase imbalance is demonstrated. The transmitter is design for 2.2 GHz to 2.3 GHz operation. At the center frequency 2.25 GHz, the measured small-signal gain is 8.2 dB, the input/output return loss is 21 dB/15.2 dB, the measured output power and power-added-efficiency are 25.8 dBm and 38.1% respectively at the 1-dB gain compression point and the output 3-order intercept point is at 38.3 dBm. Since both the transmitter and receiver integrate bandpass filters, good selectivity and stop-band rejection are achieved. Furthermore, for the garmonic suppression of transmitter, a better than -49.4 dBc suppression from 2nd to 5th harmonic output at the 1-dB gain compression point is also demonstrated.
This study also proposes a simple design flow with design equations for the abovementioned highly-integrated RF front-end system. The performance is verified using printed-circuit-board and discrete component. Further size reduction can also be achieved by using the integrated-circuit technology.

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