Current mirror circuits and methods with guaranteed off state and amplifier circuits using same

A current mirror circuit which provides an output current in response to an input current of said current mirror being received at an input terminal thereof, wherein the output current is directly proportional to the input current over a predetermined range of input current values, and wherein the output current is offset when the input current falls outside the predetermined range, the current mirror circuit comprising:

• an output terminal;
• a first circuit coupled to the input terminal and the output terminal, the first circuit generating a current feedback signal indicative of the current received at the input terminal and providing to the output terminal the output current proportional to the current received at the input terminal;
• and
• a second circuit coupled to the input terminal, the second circuit providing an offset current to the input terminal when the current feedback signal indicates that the input current falls outside the predetermined range.

A current mirror circuit for providing an output current substantially proportional to an input current of said current mirror being received at an input terminal thereof, wherein the output current is assured of being reduced to zero, the current mirror circuit comprising:

• an input terminal for receiving the input current;
• an output terminal for providing the output current;
• offset current mirror means coupled to the input terminal for providing to the input terminal an offset current when the input current is indicative of passing a predetermined low current threshold;
• and
• current mirror means coupled to the input terminal for providing to the output terminal a current proportional to the input current in excess of the offset current.

A method for operating a current mirror circuit to provide an output current in response to an input current of said current mirror being received at an input terminal thereof, wherein the output current is substantially proportional to the input current over a predetermined range of input current values, and wherein the output current is offset when the input current falls outside the predetermined range, the method comprising the steps of:

• receiving the input current;
• generating a current feedback signal that is proportional to the input current;
• providing a primary offset current when the current feedback signal indicates that the input current has passed a predetermined threshold;
• and
• generating the output current, the output current being substantially proportional to the amount by which the input current exceeds the primary offset current.