Tail current generator circuit for bipolar/MOS differential pair to set precise transconductance

摘要

Disclosed is a circuit and method for generating a tail current for a main reader amplifier ( 200 ) input stage using a scaled master differential stage ( 160 ) with a given offset to force a given output current, preceded by a balanced stage ( 150 ) to get a balanced offset. Current must be set by a feedback arrangement in the dummy master stage ( 160 ) which is a scaled version of the main reader amplifier input stage ( 200 ). The current derived in the dummy master stage ( 160 ), when appropriately scaled and used as the tail current of the main reader amplifier ( 200 ) input stage provides a precisely controlled gain.