超导量子干涉器件读出电路中匹配变压器的传输特性研究

在磁通调制超导量子干涉器件(SQUID)的读出电路中, 匹配变压器具有放大信号和阻抗匹配的功能, 是实现SQUID低噪声读出的关键元件. 利用模拟SQUID电路对匹配变压器进行性能测试, 研究了不同绕制匝数变压器的传输特性, 确定最佳绕制匝数比. 在变压器拾取SQUID电压信号的耦合网络中, 研究了不同电容对变压器传输特性的影响, 实现了变压器耦合网络参数的匹配和优化. 室温下匝数比为1:20的匹配变压器在匹配电容C=1μF时, 输出源电压增益为21.2, 带宽范围可达到210 kHz. 最后在基于磁通调制式DC SQUID读出电路中, 对匹配变压器的工作性能进行了评估与验证. 关键词： 超导量子干涉器件读出电路 匹配变压器 低噪声 传输特性

Study on transmission characteristics of matching transformer in DC superconducting quantum interference device readout

In a magnetic flux modulated DC superconducting quantum interference device (SQUID) readout, the matching transformer could realize the function of signal amplification and impedance matching, which is the key element of a low noise SQUID readout. We use a simulated DC SQUID readout to test the characteristics of matching transformer, study the transmission characteristics of transformer with different turns, and confirm its best turn ratio. In the coupling network that the transformer picks up voltage signals of SQUID, We also study the transmission characteristics of transformers with different matching capacitances, realize the matching of the parameters and the optimization in the transformer coupling network. At room temperature, for the matching transformer with a turn ratio of 1:20, when matching capacitance is 1 μF, the gain of output voltage source could reach 21.2 and its bandwidth could reach 210 kHz. Finally, in magnetic flux modulation DC SQUID readout, we evaluate the performance of the matching transformer.
Keywords： SQUID readout matching transformer low noise transmission