Class AB output stage and method for providing wide supply voltage range

A method of operating a class AB output stage at a low supply voltage, comprising:

• (a) providing a first output transistor having a first electrode coupled to a first reference voltage, a second electrode coupled to an output conductor, and a control electrode coupled to a first conductor, and a second output transistor having a first electrode coupled to a second reference voltage, a second electrode coupled to the output conductor, and a control electrode coupled to a second conductor;
• (b) sourcing at least a portion of a first input current flowing in a first input conductor through first and second electrodes of a first transistor having a control electrode coupled to the first conductor and sinking at least a portion of a second input current flowing in a second input conductor through first and second electrodes of a second transistor having a control electrode coupled to the second conductor;
• and
• (c) applying a first bias voltage to a control electrode of a third transistor having a first electrode coupled to the first input conductor and a second electrode coupled to the second conductor, and applying a second bias voltage to a control electrode of a fourth transistor having a first electrode coupled to the second input conductor and a second electrode coupled to the first conductor.

A class AB output stage operable at a low supply voltage, comprising:

• (a) a first output transistor having a first electrode coupled to a first reference voltage, a second electrode coupled to an output conductor, and a control electrode coupled to a first conductor, and a second output transistor having a first electrode coupled to a second reference voltage, a second electrode coupled to the output conductor, and a control electrode coupled to a second conductor;
• (b) means for sourcing at least a portion of a first input current flowing in a first input conductor through first and second electrodes of a first transistor having a control electrode coupled to the first conductor and for sinking at least a portion of a second input current flowing in a second input conductor through first and second electrodes of a second transistor having a control electrode coupled to the second conductor;
• and
• (c) means for applying a first bias voltage to a control electrode of a third transistor having a first electrode coupled to the first input conductor and a second electrode coupled to the second conductor, and applying a second bias voltage to a control electrode of a fourth transistor having a first electrode coupled to the second input conductor and a second electrode coupled to the first conductor.