Current switch circuit having an active load

In a current switch circuit which includes:

• at least one input switch transistor and a reference switch transistor connected between first and second reference potentials;
• a first current source connected between the emitters of said switch transistors and said second reference potential;
• the base of said reference transistor connected to an input reference potential and the base of said at least one input transistor connected to a source of an input signal, the improvement comprising:
• second and third current sources connected between said first reference potential and the collectors of said input and reference switch transistors, respectively, the current from said second and third current sources being less than the current in said first current source and tending to flow in the same direction between said first and second reference potentials;
• first and second means connected between said first reference potential and the collectors of said input reference switch transistors, respectively, for supplying supplementary current to said first current source when said respective switch transistors are conductive;
• and
• first and second means connected to said second and third current sources, respectively, for diverting the current from said second and third current source when said respective switch transistors are non-conductive.

In a current switch circuit which includes at least one input switch transistor and a reference switch transistor connected between a first reference potential and a current sink, the base of said reference transistor connected to an input reference potential and the base of said at least one input transistor connected to a source of an input signal, the improvement comprising:

• a current source connected between said first reference potential and the collector of either said reference switch transistor or said at least on input switch transistor, the current from said current source being less than the current in said sink;
• means, connected between said first reference potential and the collector of the switch transistor to which said current source is connected, for supplying supplementary current to said current sink when the switch transistor to which said current source is connected is conductive;
• and
• means, connected to said current source, for diverting said source current when said switch transistor to which said current source is connected is non-conductive.

In a current switch circuit which includes at least one input switch transistor and a reference switch transistor connected between a first reference potential and a current sink, the base of said reference transistor connected to an input reference potential and the base of said at least one input transistor connected to a source of an input signal, the improvement comprising:

• first and second current sources connected between said first reference potential and the collectors of said input and reference switch transistors, respectively, the current from each of said current sources being less than the current in said sink;
• first and second means connected between said first reference potential and the collectors of said input and reference switch transistors, respectively, for supplying supplementary current to said current sink when said respective switch transistors are conductive;
• and
• first and second means connected to said first and second current sources, respectively, for diverting the current from said sources when said respective switch transistors are non-conductive.

A plurality of current switch circuits having common reference potentials, each said current switch circuit comprising:

• at least one input switch transistor and a reference switch transistor connected between a first reference potential and a current sink, the base of said reference transistor connected to an input reference potential and the base of said at least one input transistor connected to a source of an input signal;
• a current source connected between said first reference potential and the collector of either said at least one input switch transistor or said reference switch transistor, the current from said current source being less than the current in said sink;
• means, connected between said first reference potential and the collector of the switch transistor to which said current source is connected, for supplying supplementary current to said current sink when the switch transistor to which said current source is connected is conductive;
• and
• means, connected to said current source, for diverting said source current to a second reference potential when the switch transistor to which said current source is connected is non-conductive;
• and further comprising:
• means connected to each of said current sources of each current switch for controlling the magnitude of current from said current sources.

A plurality of current switch circuits having common reference potentials, each said current switch circuit comprising:

• at least one input switch transistor and a reference switch transistor connected between a first reference potential and a current sink, the base of said reference transistor connected to an input reference potential and the base of said at least one input transistor connected to a source of an input signal;
• first and second current sources connected between said first reference potential and the collectors of said input and reference switch transistors, respectively, the current from each of said current sources being less than the current in said sink;
• first and second means connected between said first reference potential and the collectors of said input and reference switch transistors, respectively, for supplying supplementary current to said current sink when said respective switch transistors are conductive;
• and
• first and second means connected to said first and second current sources, respectively, for diverting the current from said source currents when said respective switch transistors are non-conductive.