| 摘要 |
A thin film dc SQUID and its driving electronic circuitry configured with very high symmetry. The SQUID loop is formed with four holes (24, 25, 26, 27) at the respective ends of crossed slits (22, 23). Each of these holes forms a single turn secondary (24, 25, 26, 27) for symmetrically arranged pairs of modulation coils and signal coils. The geometrical placement of the modulation coil transformers with respect to the signal coil transformers results in a device which nominally has no mutual inductance between the two groups of coils when the SQUID is biased for normal operation. The external driving circuit (75-85) is configured to preserve the highly balanced nature of the chip and forces equal magnitudes of current to flow in all four of the bias leads.
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