2.4 GHz無線網路晶片射頻輸出於開機IQ校正時產生諧波信號的研究

Abstract

本論文探討無線網路晶片在開機的IQ 校正時，射頻介面會產生±80 MHz 諧波的訊號輸出，使用頻譜分析儀觀察其特性，會有超出工作頻率2.4 GHz ~ 2.5 GHz的訊號出現。 實驗結果顯示，透過TX IQ、 RX IQ跟VGA (Variable Gain Control Amplifier) 的參數調整，可達到沒有輸出諧波目的，雖然透過這三個方式可以解決，但是使用時還是需考量頻偏跟訊號品質的問題。

The RF output of a wireless networking chip is found to generate ±80 MHz harmonics, which are located outside the 2.4 GHz ~ 2.5 GHz WLAN operating frequency range, during the power-on IQ calibration process. These harmonics are found to originate from the 80 MHz sampling frequency used by the baseband processor. Experimental results show that the parameters can be adjusted via the TX IQ, RX IQ and VGA (Variable Gain Control Amplifier) parameter adjustment, and thus achieve the purpose of no output harmonic, although these adjustments can solve the harmonic problem, their uses are constrained to not causing frequency offset and signal quality issues.