Base bias current compensator

Claim 1

A base bias current compensator to substantially supply base current requirements of a reference transistor which would otherwise have to be supplied by the associated circuitry, said reference transistor having a particular polarity and operating at a predetermined collector current and having a base, and having a reference current gain characteristic, comprising, in combination: a current source for substantially supplying a current in a ratio to said predetermined collector current; a first transistor, of same polarity as said reference transistor, having a first transistor emitter interconnected to said current source, substantially receiving said current in a ratio to said predetermined collector current, and having a current gain characteristic related to said reference current gain characteristic and having a first transistor base substantially drawing a predetermined fraction of said predetermined collector current; a second transistor, of opposing polarity to said reference transistor, having a second transistor collector interconnected to said base of said first transistor for supplying a second collector current to said first transistor base, said second transistor having a second predetermined transconductance characteristic, and a second transistor base and emitter; and a third transistor, of same polarity as said second transistor, having a third transistor collector interconnected to said base of said reference transistor, for substantially supplying a predetermined base current to said base of said reference transistor, said third transistor including a base and an emitter interconnected, respectively, to said base and said emitter of said second transistor, said third transistor having a third predetermined transconductance characteristic being in a substantially predetermined ratio to said second transconductance characteristic, whereby a third collector current is provided to said base of said reference transistor which is in a predetermined ratio to said second collector current; and a feedback amplifier having an input interconnected to said first transistor emitter and an output interconnected to said bases of said second and third transistors, whereby said second collector current may be adjusted to provide said predetermined fraction of said predetermined collector current to said base of said first transistor, and whereby said third collector current is provided to said base of said reference transistor substantially in an amount required for said reference transistor to provide said predetermined collector current.