K頻帶降頻混波器與Ku頻帶升頻混波器

Abstract

本論文設計,製作,量測出一個K頻帶降頻混波器與一個Ku頻帶升頻混波器 。降頻混波器採用五個開口環式混波器,並在之前加一個鏡像頻率抑制的 濾波器來防止外界的鏡像頻率訊號干擾中頻信號。五個開口的環式混波器 可以改良傳統的四個開口的環式混波器空橋的問題而且它可以容易地在二 極體之前加匹配電路，使變頻損耗降低。另一方面由於可以很容易在二極 體上外加電壓，可以使LO所須的功率降低。降頻混波器的RF頻段 為18.2-18.7GHz, LO頻段為19.45GHz, IF信號為0.75-1.25GHz。鏡像頻率 抑制的濾波器在鏡像頻率的抑制超過20dB。變頻損耗在RF頻段小於6.5dB, LO功率為6dBm,外加偏壓電流為3.3mA。LO to RF和LO to IF的阻隔皆大 於20dB。升頻混波器採用單端電阻性混波器,它具有低失真,低的交互調變 特性。升頻混波器IF頻段為0.9-1.4GHz, LO頻段為13.2GHz, RF信號 為14.1-14.6GHz。變頻損耗在IF頻段小於10.5dB,最低的變頻損耗為8.33 dB,當LO功率為8dBm,外加偏壓為-0.65V時。LO to RF和LO to IF的阻隔皆 大於20dB。 In this project, designed, a K-band downconverter mixer and a Ku-bandupconverter mixer are fabricated and measured. We chose a five port ring hybridmixer structure for downconverter, and we added an image rejection filter infront of this mixer to prevent the image frequency to degrade the IF signal.This five port ring hybrid mixer can solve the problem of complex structure ofairbridge or crossing transmission lines when using the rat- race structure, andit is easier to apply dc bias current which can reduce LO power requirement. Inthis downconverter mixer, RF frequency=18.2-18.7GHz, LO frequency=19.45GHz, andIF frequency=0.75-1.25GHz. The image frequency rejection is larger than 20dB inthe image rejection filter. Conversion loss is lower than 6.5 dB when LO poweris 6dBm and DC bias current is 3.3mA. The LO to RF isolation and LO to IFisolation are larger than 20dB.We selected the single resistive mixer structurefor upconverter, because it has the characteristic of low distortion and lowintermodulation. In this upconverter mixer, the IF frequency is 0.9-1.4GHz, LOfrequency is 13.2GHz, and RF frequency is 14.1-14.6GHz. Conversion loss islower than 10.5dB and the minimum conversion loss is 8.33dB which LO power is8dBm and dc bias is -0.65V. The LO to RF isolation and LO to IF isolation arelarger than 20dB.