Reference current source for low supply voltage operation

An integrated circuit current generator for operation at low supply voltages from first and second power supply connections, comprising:

• first and second branches, each connected between said first and second power supply connections, and an output branch connected between said second power supply connection and a reference current output terminal, each said branch comprising a series combination of transistors;
• a current-defining element, connected to provide current between said first branch and said second power supply connection;
• a pair of cross-coupled transistors of a first majority carrier conduction type, coupled together in a cross-coupled configuration, and each series-connected into a respective one of said first and second branches;
• a pair of mirrored transistors of said first majority carrier conduction type, coupled together in a current mirror configuration, and each series-connected into a respective one of said first and second branches;
• a matched pair of bias transistors of a second majority carrier conduction type, having control terminals thereof connected together, and each connected to provide current between said first power supply connection and a respective one of said first and second branches;
• an additional transistor of said first majority carrier conduction type, connected to limit the voltage across the one of said mirrored transistors in said second branch;
• said output branch including a first output transistor connected to follow at least one of said cross-coupled transistors in a mirrored relationship, in series with a second output transistor connected to follow said mirrored transistors in a mirrored relationship.

An integrated circuit current generator for operation at low supply voltages from first and second power supply connections, comprising:

• a first branch having first and second transistors therein operatively connected, in series with a current-defining element, between said first and second power supply connections;
• a second branch having third and fourth transistors therein operatively connected in series between said first and second power supply connections;
• said fourth transistor having a control terminal connected in common with a respective control terminal of said second transistor in a current mirror relationship, and said first and third transistors also being mutually interconnected;
• a diode connection connected to limit the voltage across said fourth transistor;
• an output branch having a first output transistor and a second output transistor therein connected in series between a reference current output terminal and said second power supply connection, said first output transistor having a control terminal connected in common with said control terminal of said third transistor, and said second output transistor having a control terminal connected in common with said control terminal of said fourth transistor.

An integrated circuit current generator for operation at low supply voltages from first and second power supply connections, comprising:

• a first branch having first and second transistors therein operatively connected, in series with a current-defining element, between said first and second power supply connections;
• a second branch having third and fourth transistors therein operatively connected in series between said first and second power supply connections;
• said fourth transistor having a control terminal connected in common with a respective control terminal of said second transistor in a current mirror relationship, and said first and third transistors also being mutually interconnected;
• an additional transistor connected to limit the voltage across said fourth transistor;
• an output branch having a first output transistor and a second output transistor therein connected in series between a reference current output terminal and said second power supply connection, said first output transistor having a control terminal connected in common with said control terminal of said third transistor, and said second output transistor having a control terminal connected in common with said control terminal of said fourth transistor.

An integrated circuit current generator for operation at low supply voltages from first and second power supply connections, comprising:

• a first branch having first and second transistors therein operatively connected, in series with a current-defining element, between said first and second power supply connections;
• a second branch having third and fourth transistors therein operatively connected in series between said first and second power supply connections;
• said fourth transistor having a control terminal connected in common with a respective control terminal of said second transistor in a current mirror relationship;
• said first and third transistors being bipolar and being mutually interconnected;
• an additional bipolar transistor, having a base-emitter junction thereof connected to shunt the series combination of said fourth transistor with a base-collector junction of said third transistor;
• an output branch having a first output transistor and a second output transistor therein connected in series between a reference current output terminal and said second power supply connection, said first output transistor having a control terminal connected in common with said control terminal of said third transistor, and said second output transistor having a control terminal connected in common with said control terminal of said fourth transistor.

An integrated circuit current generator for operation at low supply voltages from first and second power supply connections, comprising:

• a first branch having first and second transistors therein operatively connected, in series with a current-defining element, between said first and second power supply connections;
• a second branch having third and fourth transistors therein operatively connected in series between said first and second power supply connections;
• said fourth transistor having a control terminal connected in common with a respective control terminal of said second transistor in a current mirror relationship, and said first and third transistors also being mutually interconnected;
• said first, second, third, and fourth transistors all having a first majority carrier conduction type;
• and further comprising first and second bias transistors, of a second majority carrier conduction type, connected to provide currents from said first power supply connection to said first and second branches respectively;
• an additional transistor of said first majority carrier conduction type, connected to draw current from control terminals of said bias transistors, and connected to limit the voltage across said fourth transistor;
• an output branch having a first output transistor and a second output transistor therein connected in series between a reference current output terminal and said second power supply connection, said first output transistor having a control terminal connected in common with said control terminal of said third transistor, and said second output transistor having a control terminal connected in common with said control terminal of said fourth transistor.