ABSTRACT
VBG is a bandgap voltage of silicon. It can be seen by formula (2) that VBG is having a negative temperature coefficient.
Proportional to the absolute temperature difference between the emitter voltage of - transistors operate at different current densities, their base. If two similar transistors (IS1 = IS2) bias collector current respectively nI0 and I0, and their base currents are ignored, then equation (1): ∆ VBE exhibits a positive temperature coefficient, and the temperature coefficient is temperature-independent constant. The weighted positive voltage, the negative temperature coefficient of the sum, can get an approximate temperature-independent reference voltage. Here direct output reference voltage. By bipolar transistors Q1, Q2 and R1 form a current proportional to absolute temperature:
I V N
R T ln( )
= (3)
( )= + ⋅ ⋅V V
R R
(4)
It is obtained by analyzed the ratio of resistor R2 and R1.
