# US 10,122,352 B1 · Current driver system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,122,352 B1 - Document ID: US10122352B1 - Status: Granted - Kind: B1 - Application number: 15/972,995 - Filed: 2018-05-07 - Granted: 2018-11-06 - Earliest claimed: 2018-05-07 - Assignees: Northrop Grumman Systems Corporation - Applicants: Donald L. Miller; Quentin P. Herr - Inventors: Donald L. Miller; Quentin P. Herr - Web page: https://patentgrep.com/patent/US10122352B1 ## CPC - H03K 3/38: by the use, as active elements, of superconductive devices - G11C 11/16: using elements in which the storage effect is based on magnetic spin effect - G11C 11/1655: {Bit-line or column circuits} - G11C 11/1657: {Word-line or row circuits} - G11C 11/1675: {Writing or programming circuits or methods} - G11C 11/44: using super-conductive elements, e.g. cryotron - H03K 19/1952: {with electro-magnetic coupling of the control current} - H10N 60/805: {for Josephson-effect devices} - H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M) - G11C: STATIC STORES (semiconductor memory devices H10B) - H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR ## Abstract One example includes a current driver system. The system includes a current source configured to provide a source current to a transition node. The system also includes a Josephson latch comprising at least one Josephson junction stage. The at least one Josephson junction stage can be configured to conduct the source current from the transition node as a current-clamped bias current in a deactivated state of the Josephson latch. The Josephson latch can be configured to activate in response to the bias current and a trigger pulse to switch the at least one Josephson junction stage to a voltage state to conduct at least a portion of the source current from the transition node as an output current to a load in response to activation of the Josephson latch. ## Claims ### Claim 1 A current driver system comprising: a current source configured to provide a source current to a transition node; and a Josephson latch comprising at least one Josephson junction stage, the at least one Josephson junction stage being configured to conduct the source current from the transition node as a current-clamped bias current in a deactivated state of the Josephson latch, the Josephson latch being configured to activate in response to the bias current and a trigger pulse to switch the at least one Josephson junction stage to a voltage state to conduct at least a portion of the source current from the transition node as an output current to a load in response to activation of the Josephson latch. ### Claim 2 (depends on 1) The system of claim 1, wherein the Josephson latch further comprises at least one current distribution stage each configured to provide a respective at least one portion of the bias current to the respective at least one Josephson junction stage, each of the at least one current distribution stage comprises: a bias inductor coupled to the transition node and being configured to conduct the respective at least one portion of the bias current; and a clamping device coupled to the bias inductor and being configured to clamp the respective at least one portion of the bias current at a predetermined amplitude. ### Claim 3 (depends on 2) The system of claim 2, wherein the at least one current distribution stage comprises a first current distribution stage configured to conduct a respective first portion of the bias current to a respective first Josephson junction stage and at least one remaining current distribution stage configured to conduct a respective at least one remaining portion of the bias current to a respective at least one remaining Josephson junction stage, wherein the bias inductor associated with the first current distribution stages has an inductance that is less than the bias inductor associated with the remaining at least one current distribution stage to increase an amplitude of the first portion of the bias current relative to the at least one remaining portion of the bias current. ### Claim 4 (depends on 2) The system of claim 2, wherein the clamping device is configured as a Josephson junction configured to trigger at approximately the predetermined amplitude of the respective at least one portion of the bias current to clamp the at least one portion of the bias current at approximately the predetermined amplitude. ### Claim 5 (depends on 2) The system of claim 2, wherein the clamping device is configured as a tunable superconducting quantum interference device (SQUID) configured to trigger at approximately the predetermined amplitude of the respective at least one portion of the bias current to clamp the at least one portion of the bias current at approximately the predetermined amplitude, wherein the predetermined amplitude is programmable. ### Claim 6 (depends on 1) The system of claim 1, wherein the Josephson latch comprises a plurality of current distribution stages configured to conduct a respective plurality of portions of the bias current to a respective plurality of Josephson junction stages. ### Claim 7 (depends on 6) The system of claim 6, wherein each of the plurality of current distribution stages comprises a current clamping device configured to clamp an amplitude of each of the respective plurality of portions of the bias current at a predetermined amplitude. ### Claim 8 (depends on 6) The system of claim 6, wherein the Josephson latch further comprises at least one resistor that each interconnects a pair of the plurality of Josephson junction stages to substantially mitigate circulating currents in the Josephson latch. ### Claim 9 (depends on 6) The system of claim 6, wherein the Josephson latch has a critical current threshold corresponding to an activation amplitude of the bias current that is associated with a quantity of the plurality of Josephson junction stages. ### Claim 10 (depends on 1) The system of claim 1, wherein the Josephson latch further comprises an input Josephson junction coupled to a first Josephson junction stage of the at least one Josephson junction stage, the input Josephson junction being configured to cancel a negative fluxon generated by the trigger pulse that is provided as a reciprocal quantum logic (RQL) pulse. ### Claim 11 A current driver system comprising: a current source configured to provide a source current to a transition node; and a Josephson latch comprising a plurality of Josephson junction stages and at least one resistor that each interconnects a pair of the plurality of Josephson junction stages, the plurality of Josephson junction stages being configured to conduct the source current from the transition node as a respective plurality of bias currents in a deactivated state of the Josephson latch, the Josephson latch being configured to activate in response to the bias current and a trigger pulse to switch the at least one Josephson junction stage to a voltage state to conduct at least a portion of the source current from the transition node as an output current to a load in response to activation of the Josephson latch. ### Claim 12 (depends on 11) The system of claim 11, wherein the Josephson latch further comprises a plurality of current distribution stages configured to provide the respective plurality of portions of the bias current to the respective plurality of Josephson junction stages, each of the plurality of current distribution stages comprises: a bias inductor coupled to the transition node and being configured to conduct the respective at least one portion of the bias current; and a clamping device coupled to the bias inductor and being configured to clamp the respective at least one portion of the bias current at a predetermined amplitude. ### Claim 13 (depends on 12) The system of claim 12, wherein the plurality of current distribution stages comprises a first current distribution stage configured to conduct a respective first portion of the bias current to a respective first Josephson junction stage and at least one remaining current distribution stage configured to conduct a respective at least one remaining portion of the bias current to a respective at least one remaining Josephson junction stage, wherein the bias inductor associated with the first current distribution stages has an inductance that is less than the bias inductor associated with the remaining at least one current distribution stage to increase an amplitude of the first portion of the bias current relative to the at least one remaining portion of the bias current. ### Claim 14 (depends on 12) The system of claim 12, wherein the clamping device is configured as a Josephson junction configured to trigger at approximately the predetermined amplitude of the respective at least one portion of the bias current to clamp the at least one portion of the bias current at approximately the predetermined amplitude. ### Claim 15 (depends on 11) The system of claim 11, wherein the Josephson latch further comprises an input Josephson junction coupled to a first Josephson junction stage of the at least one Josephson junction stage, the input Josephson junction being configured to cancel a negative fluxon generated by the trigger pulse that is provided as a reciprocal quantum logic (RQL) pulse. ### Claim 16 A current driver system comprising: a current source configured to provide a source current to a transition node; and a Josephson latch coupled to the transition node and comprising: a plurality of Josephson junction stages being configured to conduct the source current from the transition node as a respective plurality of bias currents in a deactivated state of the Josephson latch; and a plurality of current distribution stages each comprising a bias inductor, the plurality of current distribution stages being configured to conduct a respective plurality of portions of the bias current to the respective plurality of Josephson junction stages, the bias inductor associated with a first one of the plurality of current distribution stages has an inductance that is less than the bias inductor associated with the remaining at least one of the plurality of current distribution stages; wherein the Josephson latch is configured to activate in response to the bias current and a trigger pulse to switch the plurality of Josephson junction stages to a voltage state to conduct at least a portion of the source current from the transition node as an output current to a load in response to activation of the Josephson latch. ### Claim 17 (depends on 16) The system of claim 16, wherein each of the plurality of current distribution stages comprises a current clamping device configured to clamp an amplitude of each of the respective plurality of portions of the bias current at a predetermined amplitude. ### Claim 18 (depends on 17) The system of claim 17, wherein the clamping device is configured as a Josephson junction configured to trigger at approximately the predetermined amplitude of the respective at least one portion of the bias current to clamp the at least one portion of the bias current at approximately the predetermined amplitude. ### Claim 19 (depends on 16) The system of claim 16, wherein the Josephson latch further comprises at least one resistor that each interconnects a pair of the plurality of Josephson junction stages to substantially mitigate circulating currents in the Josephson latch. ### Claim 20 (depends on 16) The system of claim 16, wherein the Josephson latch further comprises an input Josephson junction coupled to a first Josephson junction stage of the at least one Josephson junction stage, the input Josephson junction being configured to cancel a negative fluxon generated by the trigger pulse that is provided as a reciprocal quantum logic (RQL) pulse.