There are two bias schemes, namely current-bias and voltage-bias, for the directly coupled readout circuit of direct current superconducting quantum interference device (dc SQUID). In order to find out the difference between two bias schemes, we present the theoretical analyses on their equivalent circuits, working point locations, and noise performances. The theoretical analysis and experimental validation prove that the voltage-bias scheme achieves a larger transfer coefficient and exhibits a better noise performance than the current-bias scheme in the reading of conventional dc SQUID.

中文翻译：

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DC SQUID 电流偏置和电压偏置读出方案之间的噪声性能比较


直流超导量子干涉仪(dc SQUID)直接耦合读出电路有两种偏置方案，即电流偏置和电压偏置。为了找出两种偏置方案之间的差异，我们对它们的等效电路、工作点位置和噪声性能进行了理论分析。理论分析和实验验证证明，在传统直流SQUID的读取中，电压偏置方案比电流偏置方案实现了更大的传输系数，并且表现出更好的噪声性能。