Feedback-controlled low voltage current sink/source

A low voltage MOSFET-configured current sink/source comprising an output node coupled to the drain of an output MOSFET, said output MOSFET being current mirror-coupled with a reference current MOSFET, said output MOSFET having its gate resistor-coupled to the gate of said reference current MOSFET and its drain coupled to the source a feedback control MOSFET of a feedback circuit containing a further current mirror circuit, said feedback control MOSFET having its gate electrode coupled to said reference current MOSFET, and being operative, in response to a drop in drain-source voltage of said output MOSFET that would otherwise cause said output MOSFET to shift from its saturation region to its linear region of operation, to turn on and thereby cause said further current mirror circuit to mirror drain current in said feedback control MOSFET through said resistor, thereby increasing the value of gate-source voltage of said output MOSFET to a value that effectively shifts the saturation-linear transition region of the drain-to-source current versus drain-source voltage of said MOSFET to a lower drain-to-source voltage range.

A circuit for coupling an output current comprising:

• a current mirror containing a first current-generating device having a first input terminal, a first output terminal and a first control terminal, and a second current-generating device having a second input terminal, a second output terminal and a second control terminal, said first input terminal being coupled to a first voltage supply terminal, said first control terminal being coupled to said second control terminal, said second input terminal being coupled to said first voltage supply terminal, said second output terminal being coupled to receive a reference current, and said first output terminal providing a prescribed output current in accordance with a first voltage applied across said first input terminal and said first output terminal, for a second voltage applied across said first control terminal and said first input terminal;
• and
• a feedback circuit coupled in a feedback path with said first current-generating device and being operative to cause said first current-generating device to maintain said prescribed current in the presence of a change in said first voltage applied across said first input terminal and said first output terminal thereof.