- 學位論文
功率放大器非線性度分析 與毫米波次諧波混頻器電路設計
Power Amplifier Nonlinearity Analysis and Millimeter-wave Sub-harmonically Pumped Mixer Circuit Designs
摘要
在多媒體系統和個人無線通訊系統的高度需求下，消費者對於快速以及寬頻的資訊傳送的要求也比以往都還要高，但是可利用的頻寬有限；為了有效的利用頻帶，現今的數位通訊系統使用較複雜的調變架構，但必須要使用線性度更好的收發系統。 本論文主要研究於功率放大器非線性分析和毫米波非線性電路。在系統的非線性分析上，我們提出一個分析型的算式(analytical equation)來預測鄰近通道功率比(adjacent channel power ratio)。藉由量測到的交互調變失真(inter-modulation distortion ratio) 以及輸入訊號的功率密度函數(probability density function)，我們可以知道交互調變失真和鄰近通道功率比存在一個常數關係(constant correlation)，而此常數關係的差值可藉由功率密度函數來預測。此外，我們將此算式應用到毫米波系統上，即使訊號被載到毫米波頻段，常數關係的差值不會改變，只有當輸入訊號的調變方式改變，訊號的功率密度函數也跟著變的時候，常數關係的差值才會改變。在電路設計方面, 我們設計一個38到48GHz 微小型次諧波二極體混頻器和一個39到48GHz 微小型次諧波電阻式混頻器。兩顆晶片面積都只有0.72mm2。從量測結果可以印證，由於電阻式混頻器的混頻機制是線性混頻，因此比起二極體混頻器，的確有較好的線性度。
並列摘要
Due to interests in Multi-media services and personal wireless communication systems, fast and wideband data transmission is getting demanded than ever before. However, frequency band is getting crowded as well. To utilize the limited bandwidth effectively, modern digital communication systems tend to use complex digital modulation schemes which have stringent linearity specifications for the transceivers. Power amplifier nonlinearity analysis and Millimeter-wave nonlinear circuit design and are the main research point of this thesis. We present an analytical expression to show correlation between the IM3R and the ACPR for W-CDMA signal based on PDF observation. The calculable constant correlation applies to all kinds of amplifiers and applies to distorted region above P1dB as long as the IM5R is 10dB lower than IM3R. For up-link W-CDMA, the constant correlation Co is fixed at 8 dB, while the constant Co is fixed at 2 dB for down-link W-CDMA. Besides W-CDMA, PDF influence other kinds of signals. For QPSK signal, the constant Co is 6 dB, while the constant Co is 4 dB for 16-QAM, 64-QAM and 128-QAM signals. After all the discussion and derivation for signals at microwave frequency, we apply our expression to millimeter-wave frequency band. The measured results show all the constant correlation for different modulated signals hold even if the carrier frequency is at millimeter-wave frequency, and our prediction of ACPR by IM3R measurements achieves. To conclude all the measurement and calculation, the value of constant Co does not vary with circuits, carrier frequency and channel bandwidth of signals, but does vary with modulation types of signal of different PDF. On the other hand, for circuit designs, a 38-48-GHz miniature sub-harmonically pumped diode mixer with low LO input power is presented. Quasi-lumped matching topology is employed to minimize the chip size which is 0.72mm2. Additionally, a miniature Q-band monolithic subharmonically pumped resistive mixer was developed. The compact RF/IF diplex circuit and a reduced-size balun were used to minimize the chip size which results 0.72 mm2 as well. From the measurement results, the resistive mixer has the same conversion loss as the diode mixer, but has better linearity characteristics than the diode mixer.