Polarity switch incorporating Josephson devices

• US 4,210,921 A
• Filed: 06/30/1978
• Issued: 07/01/1980
• Est. Priority Date: 06/30/1978
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Faris, Sadeg M.
• Primary Examiner(s): Edlow, Martin H.
• Application Number:
  US05/920,911
• Time in Patent Office: 732 Days
• Field of Search: 307/306, 357/5, 365/162
• US Class Current: 327/528
• CPC Class Codes: G11C 11/44 using super-conductive elements, e.g. cryotron
• CPC Class Codes: H03K 17/92 by the use, as active elements, of superconductive devices
• CPC Class Codes: H03K 3/38 by the use, as active elements, of superconductive devices
• CPC Class Codes: H10N 60/10 Junction-based devices
• CPC Class Codes: Y10S 505/874 with josephson junction, e.g. squid

Abstract

A polarity switch which utilizes Josephson interferometers and low drive currents is disclosed. Single ended and double ended polarity switches which are electrically the same include a pair of circuits interconnected so that the application of a pair of signals to the circuits applies a current of one polarity or the other to a utilization circuit connected to the pair of circuits. Each of the pair of circuits includes a Josephson device which carries gate current; a current path shunting the device having a transformer secondary disposed serially in the path and another Josephson device serially disposed in the same current path. The transformer secondary is coupled to a primary through which a current is passed at the outset of the memory cycle. A current is induced in the current path of one of the pair of circuits which is in opposition to the gate current flowing in the Josephson device carrying that current. The induced current and the gate current effectively cancel one another resulting in a total current of zero flowing in the Josephson device. Then, a decoder output control line which is disposed in electromagnetically coupled relationship with both of the Josephson devices of the other of the pair of circuit switches them to the voltage state causing current to be diverted into an interconnection line which is connected to the utilization circuit.

Claims

1. A Josephson junction polarity reversing circuit comprising:

a pair of Josephson devices,

means connected to each of said devices for applying a given value of gate current to each of said pair of devices,

interconnection means connected to said pair of devices, and

means connected to said pair of devices for applying opposite polarity currents of at most said given value of gate current to said interconnection means.

2. A Josephson junction polarity reversing circuit according to claim 1 further including utilization means disposed in series with said interconnection means.

3. A circuit according to claim 1 wherein said a pair of Josephson junction devices are multi junction interferometers.

4. A circuit according to claim 1 wherein said means for applying a given value of gate current is a source of direct current.

5. A circuit according to claim 1 wherein said means for applying a given value of gate current is a pulsed source of direct current.

6. A circuit according to claim 1 wherein said interconnection means is conductor of superconducting material.

7. A circuit according to claim 1 wherein said means connected to said pair of devices for applying opposite polarity currents includes means connected to said circuit for cancelling said given value of gate current in one of said pair of devices and, means connected to said circuit for diverting said given value of gate current from the other of a said pair of devices to said interconnection means via said one of said pair of devices.

8. A circuit according to claim 1 wherein said means connected to said pair of devices for applying opposite polarity currents includes a tranformer winding disposed in parallel with each of said pair of devices, a Josephson junction disposed in series in each said transformer winding, transformer means disposed in electromagnetically coupled relationship with each said a transformer winding for applying a cancellation current equal to said given value of gate current to one of said pair of devices and control means disposed in electromagnetically coupled relationship with one of said devices and one of said junctions and the other of said devices and the other of said junctions operable to switch the other of said pair of devices and the other of said junctions.

9. A circuit according to claim 2 wherein said utilization means is a superconductive memory cell which requires the application of bipolar currents to store binary information.

10. A circuit according to claim 12 wherein said utilization device is a logic circuit responsive to applied bipolar currents.

11. A circuit according to claim 1 further including means for eliminating circulating currents disposed in series in said interconnection means.

12. A circuit according to claim 7 wherein said means connected to said circuit for cancelling said given value of gate current in one of said pair of devices includes a transformer winding disposed in parallel with each of said pair of devices, and means disposed in electromagnetically coupled relationship with each said a transformer winding for applying a current to said one of said pair of devices of equal magnitude but of opposite polarity to said given value of current.

13. A circuit according to claim 7 wherein said means for diverting said given value of gate current from the other of said pair of devices includes a Josephson junction device disposed in series in each said transformer winding, and control means disposed in electromagnetically coupled relationship with said pair of devices operable to switch the other of said pair of devices.

14. A circuit according to claim 7 wherein said means for diverting said given value of gate current from the other of said pair of devices includes a Josephson junction device disposed in series in each said transformer winding, and control means disposed in electromagnetically coupled relationship with said pair of devices operable to switch the other of said pair of devices and an associated Josephson junction.

15. A circuit according to claim 8 further including a separately actuable current source connected in series with each said transformer means.

16. A circuit according to claim 12 further including control means disposed in electromagnetically coupled relationship with one of said devices and one of said junctions and the other of said devices and the other of said junctions operable to switch the other of said pair of devices and the other of said junctions.

17. A circuit according to claim 12 wherein said means for applying a current of equal magnitude but of opposite polarity to said given value of current includes another transformer winding electromagnetically coupled relationship with each said a transformer winding and a separately actuable current source connected in series with each said another transformer winding.

18. A circuit according to claim 17 further including control means disposed in electromagnetically coupled relationship with one of said devices and one of said junctions and the other of said devices and the other of said junctions operable to switch the other of said pair of devices and the other of said junctions.