Sub-rail voltage regulator with low stand-by current and high load current

摘要

The sub-rail voltage generator includes three sections: an output stage having an output terminal that provides a sub-rail output voltage; a voltage divider network that includes two voltage nodes; and a current gain stage connected between the voltage nodes of the voltage divider and the output terminal of the output stage. The current gain stage includes two sections. The first section includes a first transistor connected between a respective voltage divider voltage node and the output terminal for sensing the output load current demanded at the output terminal. A current is produced in the first transistor responsive to a sourcing load current demanded at the output terminal. A current mirror is coupled to the first transistor to "mirror" the current through the first transistor. This mirrored current is provided to a first output transistor in the output stage as a first bias current. The first output transistor provides the demanded output current responsive to the first bias current. The second section of the current gain stage is the mirror image of the first section and is responsive to a sinking load current demanded at the output terminal.