| 摘要 |
A successive approximation analogue to digital converter includes at least one superconducting loop 30. Non-superconducting reference inductors 38 provide flux quanta reference levels. Switchable screens 34 are interposed between the inductors 38 and lobes 31 in an addition/subtraction superconducting loop 30. Each screen 34, when superconducting, screens the corresponding lobe 31 from the inductor 38. When a sufficiently large current is provided to screen 34 it becomes non-superconducting and links flux from inductor 38 to lobe 31. An analogue signal is supplied to a drive loop 36 and the corresponding magnetic flux is coupled to a sensing lobe 32 and concentrated at a flux concentrating lobe 33. The reference fluxes are selectively coupled by screens 34 into the addition/subtraction superconducting loop 30 until a magnetometer 40 indicates zero net flux through the concentrating lobe 33, this corresponding to completion of the conversion. In an alternative embodiment the reference fluxes are provided from a store formed by multi-level superconducting loops (Fig 8). <IMAGE> |
