Design and development of SIS mixers for ALMA band 8
Design and development of SIS mixers for ALMA band 8
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DOI：
10.1109/tasc.2005.849889
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发表时间：
2005-06
影响因子：
1.8
通讯作者：
W. Shan;Sheng-Cai Shi;T. Matsunaga;M. Takizawa;Akira Endo;Takashi Noguchi;Y. Uzawa
中科院分区：
文献类型：
--
作者：
W. Shan;Sheng-Cai Shi;T. Matsunaga;M. Takizawa;Akira Endo;Takashi Noguchi;Y. Uzawa
在本文中，我们报告的设计和实验结果的固定调谐超导体-绝缘体-超导体（SIS）混频器的阿塔卡马大毫米/亚毫米阵列（阿尔马）波段8（385-500 GHz）接收机。铌基SIS结的电流密度为10 kA/cm/sup 2/和一个微米的大小（制造与两步剥离过程），以实现阿尔马接收机规格，这需要宽的频率覆盖范围以及低噪声温度。双结（PCTJ）被设计成在能带中心谐振，以调谐出结的几何电容。波导-微带探针被优化为在探针的馈电点处具有几乎与频率无关的阻抗，从而使得在宽频带上匹配低阻抗PCTJ容易得多。此外，超导磁体固定到紧凑的混频器块，以提供有效的磁场耦合的设计。SIS混频器的最小双边带接收机噪声温度在频带中心为108 K，在整个频带内（中频范围为4-8 GHz）的温度低于167 K。
In this paper, we report on the design and experimental results of a fix-tuned Superconductor-Insulator-Superconductor (SIS) mixer for Atacama Large Millimeter/submillimeter Array (ALMA) band 8 (385-500 GHz) receivers. Nb-based SIS junctions of a current density of 10 kA/cm/sup 2/ and one micrometer size (fabricated with a two-step lift-off process) are employed to accomplish the ALMA receiver specification, which requires wide frequency coverage as well as low noise temperature. Parallel-connected twin junctions (PCTJ) are designed to resonate at the band center to tune out the junction geometric capacitance. A waveguide-microstrip probe is optimized to have nearly frequency-independent impedance at the probe's feed point, thereby making it much easier to match the low-impedance PCTJ over a wide frequency band. In addition, a superconducting magnet fixed onto the compact mixer block to provide efficient magnetic field coupling is designed. The SIS mixer demonstrates a minimum double-sideband receiver noise temperature of 108 K at the band center and temperatures of less than 167 K over the whole band (for an intermediate-frequency range of 4-8 GHz).