應用於天文接收機之Q頻段可變增益低雜訊放大器、G頻段二倍頻器與相位陣列收發系統之平方混合器研究

Abstract

在這本論文由以下三個部分組成，一個Q頻段具主動負載之可變增益低雜訊放大器和一個G頻段具高三、四次諧波抑制主動二倍頻器的設計與量測結果。 首先是預計作為Q頻段接收機之可變增益低雜訊放大器，使用的製程為90奈米金氧半場效電晶體，電路第一級使用源極退化電感已達到雜訊和增益的最佳匹配，第二及第三級作為增益控制使用n-type金氧半場效電晶體作為可變主動負載來達到增益控制並且在增益降低的同時減少電路的功耗，以達到接收機更高的功率效率。量測結果顯示此低雜訊可變增益低雜訊放大器具有19 GHz (29-48GHz) 並且在32 GHz的頻率下有最高增益19 dB以及最低雜訊5.3 dB，8-dB增益控制範圍，在最高和最低增益下的功耗分別為25.3及14.3 mW。 第二部分提出應用於阿塔卡瑪大型毫米波陣列第四及五頻段之二倍頻器，使用的製程為90奈米金氧半場效電晶體。使用馬遜平衡器產生180°相位差訊號，並透過將偏壓點選在Class-B，利用電晶體的最高二次轉導達到倍頻效果，雖然波導管本身可以抑制基頻的訊號，但由於天文接收機中混頻器寬頻特性，高次諧波項依然可能被降頻至混頻器的輸出，因此本電路透過柴比雪夫低通濾波器以抑制三、四次諧波項。在10 dBm輸入功率下，量測結果顯示在頻率182 GHz有最高輸出功率2.3 dBm以及-7.7 dB的轉換增益，電路的輸出3-dB頻寬為158-204 GHz，擁有25.4%比例頻寬。 第三部分提出應用於300 GHz 相位陣列收發器之平方混合器，使用的製程為65奈米金氧半場效電晶體。此平方混合器之架構和推推倍頻器相似，將偏壓點選在Class-B以達到最大的混頻效果，平方混合器通過平方中頻（IF）訊號和本地振盪（LO）訊號來生成射頻（RF）信號，中頻訊號和本地振盪訊號的頻率一樣。第一級採用堆疊放大器使電路在高頻中達到高輸出高增益的效果。但是因為訊號產生器的限制，量測並不完整，只能量到頻寬內的四個頻率點，其餘皆為模擬結果。在 -10 dBm輸入功率下，量測結果顯示在頻率272 GHz有最高輸出功率-2.6 dBm以及-12.6 dB的轉換增益，電路的輸出3-dB頻寬為266-282 GHz。

This paper presents two main sections: the design and measurement results of a Q-band variable gain low noise amplifier (VGLNA) with current control and a G-band active frequency doubler with high 3rd and 4th harmonic suppression. The first part presents a Q-band variable gain low noise amplifier (VGLNA) fabricated in 90-nm COMS process. Source degeneration is used to achieve the optimal noise and gain matching at the first stage. An NMOS current control device is used at the second and third stages to achieve gain control and reduce power consumption while the circuit's gain decreases, which could enhance the efficiency of the receiver. Measurement results reveal this VGLNA offers a 19 GHz (29-48 GHz) 3-dB bandwidth and a peak gain of 19 dB appears at 32 GHz, and the lowest noise figure is 5.3 dB. An 8-dB gain control range, 25.3 and 14.3 mW power consumption at high and low gain mode respectability. The second part introduces a frequency doubler with high 3rd and 4th harmonic suppression for the ALMA band 5 fabricated in 90-nm CMOS process. Using Marchand balun to generate differential signal. The transistor is operated at class B for the highest Gm2. Although the output waveguide would block the signal from baseband, the higher harmonics may still down-convert significant RF power to the IF output because the wide bandwidth nature of mixer in radio astronomical receiver. This circuit suppresses 3rd and 4th harmonics by Chebyshev low pass filter. The measured peak conversion gain of the doubler is -7.7 dB and 2.3 dBm output power at 182 GHz with 10 dBm input power, the 3-dB bandwidth of the doubler is 158-204 GHz with 25.4% fractional bandwidth. The third part presents a square mixer applied to a 300 GHz phase-array transceiver, utilizing a 65 nm CMOS process. The architecture of this square mixer is similar to that of a push-push doubler, with the bias point set at Class-B to achieve maximum mixing performance. The square mixer generates radio frequency (RF) signals by squaring the intermediate frequency (IF) signal and the local oscillator (LO) signal, which are at the same frequency. The first stage employs a stacked amplifier to achieve high output and gain at high frequencies. However, due to the limitations of the signal generator, the measurements are not complete, and only four frequency points within the bandwidth could be measured, with the rest being simulated results. At an input power of -10 dBm, the measurement results show the highest output power of -2.6 dBm and a conversion gain of -12.6 dB at a frequency of 272 GHz, with the circuit's output 3-dB bandwidth ranging from 266 to 282 GHz.