Wide Stop-band High-temperature Superconducting Receiver Front-end Research

With the rapid development of modern communications, the requirements of receiver performances (such as stopband, noise figure and sensitivity) are higher and higher. The study of receiver front-end which has performances of wide stopband, low noise and high sensitivity has great sense.In this thesis, a high-temperature superconducting (HTS) receiver front-end with low noise figure, high sensitivity, broad stopband and strong out-of-band rejection is presented. The receiver front-end consists of a HTS bandpass filter and a low temperature low noise amplifier (LNA). By using a complex resonator structure with strong capacitive loading, the HTS bandpass filter achieves small insertion loss and good frequency selectivity, shifts the parasitic passband to 3.5 times of the center frequency as well, meanwhile, remains a compact size. Low-noise amplifier plays an important role in lowering the noise figure of receiver. In this thesis, Avago's ATF54143 is selected. In order to achieve the minimum noise figure, input and output matching have used optimum noise matching and conjugate matching respectively.Finally, a prototype of broad stopband HTS receiver front-end is fabricated and measured, whose noise figure NF is less than 0.5dB, out-of-band rejections is better than 90dB@( f 0 ?BW) and 60dB@( f 0 +BW～3. 5f 0), sensitivity is up to -93dBm. The results meet the design objectives well.