Temperature-compensated LV bipolar IC source - has amplifier with NPN transistors in common-base configuration and load resistors whose ratio determines output voltage

摘要

The source includes an operational amplifier (A), temperature compensated and having a difference (V) between the input voltages at its inverting and non-inverting terminals. The amplifier comprises two NPN transistors, mounted in common-base configuration (Q1, Q2), their collectors being connected to a source circuit (13, 14). The transistor base is connected to a third NPN transistor (Q16) with its collector to a power supply. The source circuit consists of two PNP transistors (Q13, Q14) grounded through a third PNP transistor (Q15) and connected to a current source (20). The amplifier also comprises two resistors (R1, R2) placed between the base and emitter of the first NPN transistor and, respectively emitter and amplifier input. If VBE1 is the base emitter voltage of the first NPN transistor and delta VBE is the difference between the base emitter voltages of the two NPN transistors, then the voltage V is given by V = (R2/R1) VBE1 + deltaVBE. ADVANTAGE - Can provide low voltages, in range 1.25 V down to tens of millivolts.