Superconducting analog amplifier circuits

A combination comprising:

• first and second Josephson transmission structures (JTSs);
• each JTS having an input terminal and an output terminal, and each JTS including between its input and output terminals Josephson transmission line (JTL) means and a low pass filter means;
• means for applying a first input signal to the input terminal of the first JTS, and means for applying a second input signal to the input terminal of the second JTS;
• and
• output means including an output inductive means connected between the output terminals of the first and second JTS.

A combination comprising:

• first and second Josephson transmission lines (JTLS);
• each JTL having an input terminal and an output terminal and each JTL being formed by cascading a plurality of cells between its input and output terminals;
• each cell of said plurality of cells having an input node and an output node and including an inductor connected between its input node and its output node, a bias current generator connected between its output node and a first point of reference potential and a Josephson junction connected between its output node and a second point of reference potential;
• means for applying a first input signal to the input terminal of the first JTL, and means for applying a second input signal to the input terminal of the second JTL;
• output means including an output inductive means and current limiting means connected between the output terminals of the first and second JTL;
• and
• a flux to voltage converter magnetically coupled to the output inductive means for converting the flux therethrough to a voltage.

A combination comprising:

• a Josephson transmission line (JTL) means having an input terminal and an output terminal and a plurality of cells connected in cascade between its input and output terminals;
• each cell having an input node and an output node and including an inductor connected between its input node and its output node, a bias current generator connected between its output node and a first point of reference potential and a Josephson junction connected between its output node and a second point of reference potential;
• means for applying a voltage input signal to the input terminal of the JTL;
• output means including an output inductive means and a flux release means connected between the output terminal of the JTL and a point of reference potential;
• and
• a flux to voltage converter magnetically coupled to the output inductive means for converting the flux therethrough to a voltage.

A combination comprising:

• a first input terminal for the application thereto of an input signal to be amplified and a first output terminal for producing thereat an amplified and filtered version of the input signal;
• first, second and third Josephson transmission line (JTL) sections, each JTL section having an input node and an output node, and each JTL section including at least one cell;
• wherein each cell includes first and second nodes, an inductor connected between the first and second nodes, a Josephson junction (JJ) connected between the second node and a point of reference potential;
• and a bias current generator connected to the second node for providing a bias current to the JJ;
• means connecting the input node of the first JTL section to said input terminal;
• means connecting the input nodes of the second and third JTLs to the output node of the first JTL section for causing additional signal current gain within said second and third JTL;
• and
• means connected to the output node of the second JTL section and means connected to the output node of the third JTL section for coupling their outputs to, and combining their output currents at, said output terminal.

A combination comprising:

• a first input terminal for the application thereto of an input signal to be amplified and a first output terminal for producing thereat an amplified and filtered version of the input signal;
• a first Josephson transmission line (JTL) having an input point connected to said first input terminal and having an output point;
• two additional Josephson transmission lines (JTLs), each one of said two additional JTLs having an input point connected to the output point of the first JTL, and each one of said two additional JTLs having an output point;
• means combining the outputs of the two additional JTLs and coupling their output points to said first output terminal;
• and
• wherein each one of said JTLs includes at least one cell, each cell including:
• an input node, an output node, an inductor connected between the input and output nodes of the cell, a bias current generator connected between the output node of the cell and a first point of reference potential and a Josephson junction connected between the output node of the cell and a second point of reference potential.