高頻譜純度無線發射機之射頻電路技術

RF Circuit Techniques for Wireless Transmitter with High Spectral Purity

高堃堯(Kun-Yao Kao)

指導教授 ： 林坤佑

國立臺灣大學/電機資訊學院/電信工程學研究所/博士(2015年)

https://doi.org/10.6342/NTU.2015.01734

摘要

近二十年，我們見證了無線通訊的巨大成長。對於低成本、節能、微小化、可支援多種數位通信標準之通訊設備日益增長的需求，促進了射頻收發機積體電路獲得越來越多的發展。在設計發射機路徑時，必須要保持發射信號的高頻譜純度，以避免電路內非線性現象引起的頻帶外發射以及信號雜訊比的降低。

本篇論文描述了發射機路徑上的兩個關鍵基本組件，亦即壓控振盪器和功率放大器。首先本文起於發射機路徑上頻譜純度的重要性，由一給定的發射頻譜波罩探討發射機所需壓控振盪器和功率放大器的非線性規格。本文所提出的第一個電路是一個採用互補式變壓器耦合的壓控振盪器，其具有抑制來自切換對之通道熱雜訊的功能。相較於其它現有架構，可本質上改善相位雜訊以及振盪器之雜訊因子。為了深入分析相位雜訊的非線性機制，我們將回顧過去定量分析相位雜訊的理論。本文所提出的第二個電路是兩個結合相位延遲線性器之功率放大器，其可更加展延輸出功率1 dB壓縮點。電路中的非線性所引起的三階諧波失真和鄰近波道功率比將分為振幅失真以及相位失真來討論，透過加入一斜率補償的線性器，可使在複雜的數位調變下之功率倒退操作更加有效率。

關鍵字

壓控振盪器 ； 變壓器 ； 通道雜訊衰減 ； 相位雜訊 ； 功率放大器 ； 相位延遲線性器 ； 預失真 ； 增益展延

並列摘要

The last two decades have witnessed a tremendous growth in wireless communications. The increasing demands for cost-effective, power-efficient, and miniature size communication devices that support multiple digital communication standards have lead more and more developments on the integration of radio-frequency (RF) transceiver circuitry. For the transmitter path design, keeping transmitted signal with high spectral purity is essential to prevent the out-of-band emission and the reduction of signal-to-noise ratio (SNR) generated from the circuit nonlinearities.

This thesis describes the circuit design for the two crucial building blocks in the transmitter path, namely voltage-controlled oscillator (VCO) and power amplifier (PA). The significance of spectral purity in the transmitter path is arisen at the beginning.
From a given spectrum emission mask to the required nonlinear specification for the VCO and PA is discussed. The first circuit design is a complementary transformer-coupled VCO proposed to suppress the channel thermal noise coming from the switching pair, which substantially results in lower phase noise performance and a lower oscillation noise factor compared with the existing VCO architectures. In order to analyze the nonlinear phase noise mechanism in depth, the quantitative theoretical framework will be reviewed. The second circuit design is two power amplifiers (PAs) with individual phase-delay pre-distortion linearizer proposed to further extend the output 1 dB compression point (OP1dB). The impact due to circuit nonlinearity on the third-order intermodulation distortion (IMD3) and the adjacent channel power ratio (ACPR) is discussed with separate amplitude/phase distortion issues. By means of adding a slope compensation linearizer, the power back-off operation is more efficient under complex digital modulation scheme.

並列關鍵字

Voltage-controlled oscillator (VCO) ； transformer ； channel noise reduction ； phase noise ； power amplifier (PA) ； phase-delay linearizer ； pre-distortion ； gain expansion

參考文獻

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