Amplifier with fast recovery after input signal overswing

An amplifier comprising:

• first and second terminals for receiving an operating potential therebetween;
• third and fourth terminals for input and output signals, respectively;
• a first transistor of a first conductivity type having an emitter electrode connected to said first terminal, having a base electrode, and having a collector electrode coupled to said fourth terminal;
• direct current conductive impedance means connecting said first transistor collector electrode to said second terminal;
• second and third transistors of a second conductivity type, each having a collector electrode coupled to said first transistor base electrode, each having an emitter and a base electrode, said first and said second conductivity types being complementary to each other;
• first and second conductive means, one having higher impedance for signal than the other, said first conductive means connecting said third transistor emitter electrode to said second transistor emitter electrode, said second conductive means connecting said third transistor emitter electrode to said second terminal;
• further means connecting said second transistor in common-base amplifier configuration;
• and
• further means connecting said third transistor in common-emitter amplifier configuration including a connection of said third terminal to said third transistor base electrode.

In combination:

• a first differential amplifier, having an input circuit and an output circuit, and exhibiting a transconductance g.sub.m between its input and output circuits;
• a second differential amplifier, having an input circuit and an output circuit, and exhibiting a transconductance g.sub.m ' between its input and output circuits;
• means for coupling the input circuits of said first and said second differential amplifiers in parallel to receive an input signal potential;
• and
• a balanced to single-ended signal converter comprising a current mirror amplifier with a common terminal connected to a point of fixed potential, an input terminal and an output terminal between which the output circuits of said first and said second circuits are cross-coupled so that their combined transconductance is substantially g.sub.m -g.sub.m ' for the normal range of signals, said cross-coupled connection preventing the discharge of capacitances in the current mirror amplifier during input signal overswings.

An amplifier comprising:

• first and second terminals for receiving an operating potential;
• third and fourth terminals for receiving input signals;
• first, second, third, and fourth transistors of similar conductivity type, each having a base and an emitter and a collector electrode, the base electrodes of said first and said third transistors being connected to said third terminal, the base electrodes of said second and said fourth transistors being connected to said fourth terminal;
• first resistive means connecting the emitter electrodes of said first and said third transistors;
• second resistive means connecting the emitter electrodes of said second and said fourth transistors;
• means for direct current conductively coupling the emitter electrodes of each of said first and said second transistors to said second terminal;
• and
• balanced to single-ended signal converter means having a first input terminal to which the collector electrodes of said first and said fourth transistors are connected, having a second input terminal to which the collector electrodes of said second and said third transistors are connected, having a common terminal connected to said first terminal and direct current conductive paths between each of its first and second input terminals and its common terminal, and having an output terminal for connection of a load.

An amplifier comprising:

• first and second terminals for receiving an operating potential;
• third and fourth terminals for receiving input signals;
• first, second, third and fourth transistors of similar conductivity type, each having a base and an emitter and a collector electrode, the base electrodes of said first and said third transistors being connected to said third terminal, the base electrodes of said second and said fourth transistors being connected to said fourth terminal;
• resistive means having a first end to which the emitter electrodes of said first and said second transistors are connected and having a second end to which the emitter electrodes of said third and said fourth transistors are connected;
• means for direct current conductively coupling the first end of said resistive means to said second terminal;
• and
• balanced to single-ended signal converter means having a first input terminal to which the collector electrodes of said first and said fourth transistors are connected, having a second input terminal to which the collector electrodes of said second and said third transistors are connected, having a common terminal connected to said first terminal and direct current conductive paths between each of its first and second input terminals and its common terminal, and having an output terminal for connection to a load.

An amplifier comprising:

• first and second terminals for receiving an operating potential;
• third and fourth terminals for receiving input signals;
• first, second, third and fourth transistors of similar conductivity type, each having a base and an emitter and a collector electrode, the base electrodes of said first and said third transistors being connected to said third terminal, the base electrode of said second and said fourth transistors being connected to said fourth terminal;
• first and second constant current source means, said first constant current source means connected between said second terminal and the joined emitter electrodes of said first and said second transistors to forward bias them, said second constant current source means connected between said second terminal and the joined emitter electrodes of said third and said fourth transistors to forward bias them, the currents supplied by said first and said second constant current source means being proportioned to condition said first and said second transistors for higher transconductances than said third and said fourth transistors;
• and
• balanced to single-ended signal converter means having a first input terminal to which the collector electrodes of said first and said fourth transistors are connected, having a second input terminal to which the collector electrodes of said second and said third transistors are connected, having a common terminal connected to said first terminal and direct current conductive paths between each of its first and second input terminals and to its common terminal, and having an output terminal for connection to a load.

An amplifier comprising:

• first and second terminals for receiving an operating potential;
• third and fourth terminals for receiving input signals;
• first, second, third and fourth transistors of similar conductivity type, each having a base and an emitter and a collector electrode, the base electrodes of said first and said third transistors being connected to said third terminal, the base of electrode of said second and said fourth transistors being connected to said fourth terminal;
• first and second similar direct current conductive means having first ends connected to the respective emitter electrodes of said first and said second transistors and having second ends;
• third and fourth similar direct current conductive means having first ends connected to the respective emitter electrodes of said third and said fourth transistors, having second ends, and being of higher impedance than said first and said second direct current conductive means;
• first constant current source means connected between said second terminal and the second ends of said first and said second direct current conductive means and poled to forward bias the emitter electrodes of said first and said second transistors;
• second constant current source means connected between said second terminal and the second ends of said third and said fourth direct current conductive means and poled to forward bias the emitter electrodes of said third and said fourth transistors;
• and
• balanced to single-ended signal converter means having a first input terminal to which the collector electrodes of said first and said fourth transistors are connected, having a second input terminal to which the collector electrodes of said second and said third transistors are connected, having a common terminal connected to said first terminal and direct current conductive paths between each of its first and second input terminals and its common terminal and having an output terminal for connection to a load.

An amplifier comprising:

• first and second terminals for receiving an operating potential;
• third and fourth terminals for receiving input signals;
• first, second, third and fourth transistors of similar conductivity type, each having a base and an emitter and a collector electrode, their emitter electrodes being joined at a common interconnection, the base electrodes of said first and said third transistors being connected to said third terminal, the base electrodes of said second and said fourth transistors being connected to said fourth terminal, said first and said second transistors having similar transconductance characteristics, said third and said fourth transistors having similar transconductance characteristics differing from those of said first and said second transistors;
• means for direct current conductively coupling said common interconnection to said second terminal;
• and
• balanced to single-ended signal converter means having a first input terminal to which the collector electrodes of said first and said fourth transistors are connected, having a second input terminal to which the collector electrodes of said second and said third transistors are connected, having a common terminal connected to said first terminal and direct current conductive paths between each of its first and second input terminals and its common terminal, and having an output terminal for connecting to a load.

An amplifier comprising:

• first and second terminals for receiving an operating potential;
• third and fourth terminals for receiving input signals;
• first, second, third and fourth transistors of similar conductivity type, each having a base and an emitter and a collector electrode, the emitter electrodes of said first and said second transistors being joined at a common interconnection, the base electrodes of said third and said fourth transistors being connected respectively to said third terminal and to said fourth terminal, the emitter electrodes of said third and said fourth transistors being connected respectively to said first transistor base electrode and to said second transistor base electrode, said first and said second transistors having similar transconductance characteristics, said third and said fourth transistors having similar transconductance characteristics differing from those of said first and said second transistors;
• means for direct current conductively coupling said common interconnection to said second terminal;
• and
• balanced to single-ended signal converter means having a first input terminal to which the collector electrodes of said first and said fourth transistors are connected, having a second input terminal to which the collector electrodes of said second and said third transistors are connected, having a common terminal connected to said first terminal and direct current conductive paths between each of its first and second input terminals and its common terminal, and having an output terminal for connection to a load.

In combination:

• a driver transistor of one conductivity type having base, emitter and collector electrodes, adapted to receive an input signal between its base and emitter electrodes;
• an amplifier including a second transistor of opposite conductivity to said driver transistor, having base, emitter and collector electrodes and direct coupled at its base electrode to the collector electrode of said driver transistor, said second transistor exhibiting a capacitance at its base electrode which tends to discharge when said driver transistor cuts off and tends to drive said second transistor to cut-off;
• and
• means coupled to an electrode of said driver transistor for sensing the approach the cut-off in said driver transistor and responding to supply a charging current to said capacitance.