An SIS Mixer With $2hf/k$ DSB Noise Temperature at 163–211 GHz Band
An SIS Mixer With $2hf/k$ DSB Noise Temperature at 163–211 GHz Band
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163–211 GHz 频段 DSB 噪声温度为 2hf/k$ 的 SIS 混频器
DOI：
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发表时间：
2013
影响因子：
3.2
通讯作者：
V. Belitsky
中科院分区：
文献类型：
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作者：
B. Billade;A. Pavolotsky;V. Belitsky
我们提出了一个固定调谐，所有铌（Nb）超导体-绝缘体-超导体（SIS）混频器的设计和性能，覆盖RF频率从163到211 GHz，4-8 GHz的IF带宽。该混频器采用两个尺寸为3 μm2的Nb/Al-AlOx/Nb双结结构，每个结的RnA积为30 Ω·μ m2。本振（LO）定向耦合器的超导线与槽在接地平面上集成在SIS混频器芯片。LO耦合器的隔离端口端接一个薄层电阻为12 Ω/□的宽带阻性负载。SIS调谐电路被优化以实现双结和嵌入电路之间的最佳功率匹配。在171 GHz的双边带混频器噪声的测量表明，接收机噪声温度约为17 K，这仅仅是2 hf/k。在176 GHz LO频率下，RF损耗和IF链的估计噪声贡献分别为8 K和7.5 K，导致SIS混频器噪声为hf/2k。整个RF频段的混频器噪声性能在19至25 K之间变化。据我们所知，这是迄今为止在这些频率下报告的最佳噪声温度。
We present the design and the performance of a fixed-tuned, all niobium (Nb) Superconductor-Insulator-Superconductor (SIS) mixer covering RF frequencies from 163 to 211 GHz with 4-8 GHz IF bandwidth. The mixer uses two Nb/Al-AlOx/Nb junctions of size 3 μm2 each with the RnA product of 30 Ω·μm 2, in a twin junction configuration. An local oscillator (LO) directional coupler made of superconducting lines with slots in the ground plane is integrated on the SIS mixer chip. The isolated port of the LO coupler is terminated using a wide-band resistive load with a sheet resistance of 12 Ω/□. The SIS tuning circuitry is optimized to achieve best power match between the twin junctions and the embedding circuitry. The measurement of the double sideband mixer noise at 171 GHz shows that the receiver noise temperature is approximately 17 K, which is just 2 hf/k. The estimated noise contribution from the RF loss and the IF chain at 176 GHz LO frequency is 8 K and 7.5 K respectively, resulting in a SIS mixer noise of hf/2k . The mixer noise performance across the entire RF band varies between 19 to 25 K. This is to our knowledge the best reported noise temperature at these frequencies till now.