Differential voltage to current converter

摘要

A bipolar integrated circuit differential voltage to current converter comprises a current source and a current sink at a lower current with two parallel branches connected therebetween. Each branch comprises, from the current source, a resistor, an input transistor with an emitter connected to the resistor and a mirror transistor with an emitter connected to the current sink. The resistors have equal resistance; the input transistors have bases comprising a differential voltage input; and the mirror transistors are connected in a current mirror arrangement. An output current is taken from the junction the resistor and the emitter of the input transistor connected thereto on the output side of the mirror so as to allow the current mirror to maintain equal currents and thus equal base/emitter voltages in the input transistors. A demand current sink transistor is connected in series with the current source with a base connected to the current sink so as to take excess current from the current source not taken by the current sink and current output and thus maintain the currents through the input transistors low for minimal input loading.