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US 6,608,518 B2Granted
Superconducting single flux quantum circuit
AssigneeHitachi, Ltd.
InventorsFutoshi Furuta, Kazuo Saitoh, Kazumasa Takagi
Life of this patent
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Abstract
The problem of the disclosed technology is as follows. Although a single flux quantum circuit can fabricate a high-speed sequential circuit with ease, the initialization of the circuit is required for guaranteeing the normal operation of the circuit. However, a prior-art circuit has no initializing function, or requires the restructuring of another logic system. For solving the foregoing problem, one Josephson junction is inserted to a flux quantum storage inductor constituting the existing logic circuit, so that a pulse for performing the circuit initialization is injected to the connection point by means of a comparator.
Claims11
A superconducting single flux quantum circuit, comprising:
- a signal storing circuit, comprising:
- a first inductor;
- Josephson junctions connected to opposite ends of the first inductor, for forming a loop through which a circulating current flows between the first inductor and a grounded circuit;
- a signal input terminal connected to the one end of the first inductor via a Josephson junction, for inputting a single flux quantum pulse;
- and a clock input terminal connected to the other end of the first inductor via a Josephson junction, for inputting a clock pulse, the circulating current being caused to flow through the first inductor by the single flux quantum pulse inputted to the signal input terminal, the circulating current of the first inductor being interrupted by the clock pulse inputted to the clock input terminal during the flow of the circulating current, and a single flux quantum pulse being outputted from an output terminal withdrawn from a connection point of the clock input terminal and the first inductor;
- and
- a circulating current canceling circuit, comprising:
- a second inductor connected to a position to divide the fist inductor into roughly equal halves;
- series-connected two Josephson junctions for grounding the other end of the second inductor;
- a bias current source connected to a connection point between the series-connected two Josephson junctions, for supplying a bias current;
- an initializing pulse input terminal connected via a Josephson junction connected to the connection point between the series-connected two Josephson junctions, for inputting an initializing pulse;
- and an output terminal for outputting the state of the connection point between the series-connected two Josephson junctions,
- and, a Josephson junction being inserted in series to the one end of the inductor closer to the clock input terminal of the first inductor divided into halves.
10 more elements
A superconducting single flux quantum circuit, comprising:
- a circuit configuration constructed of series-connected first and second Josephson junctions;
- series-connected third and fourth Josephson junctions;
- a data input terminal attached to the one end of the first Josephson junction;
- a first clock input terminal attached to the one end of the third Josephson junction;
- a first data output terminal for producing an output at the connection point between the third and fourth Josephson junctions;
- a first bias current source for supplying a current to the connection point between the first and second Josephson junctions and a second bias current source for supplying a current to the connection point between the third and fourth Josephson junctions, of which the terminals on the different side from the respective connection points with the second and fourth Josephson junctions are respectively grounded;
- a first inductor connected to the connection point between the first and second Josephson junctions;
- a fifth Josephson junction connected to the connection point between the third and fourth Josephson junctions;
- a second inductor connected between the other end of the first inductor and the other end of the fifth Josephson junction;
- a sixth Josephson junction of which the one end is grounded;
- a seventh Josephson junction connected to the other end of the sixth Josephson junction;
- an eighth Josephson junction connected to the other end of the sixth Josephson junction;
- a third bias current source connected to the other end of the sixth Josephson junction;
- a second data output terminal connected to the other end of the sixth Josephson junction;
- a second clock input terminal disposed on the other end of the eighth Josephson junction;
- and a third inductor connected to the other end of the seventh Josephson junction, the side of the third inductor different from the side connected to the seventh Josephson junction being connected to the connection point between the first inductor and the second inductor,
- such that a signal inputted from the data input terminal is outputted to either of the fist data output terminal and the second data output terminal in response to the input of a signal from the first clock input terminal or the second clock input terminal.
14 more elements
Dependencies are inferred from the claim text.