A CMOS bandgap reference circuit with sub-1-V operation

This paper proposes a CMOS bandgap reference (BGR) circuit, which can succe ssfully operate with sub-1-V supply, Zn the conventional BGR circuit, the o utput voltage V-ref is the sum of the built-in voltage of the diode V-f and the thermal voltage V-T Of kT/q multiplied by a constant. Therefore, V-ref is about 1.25 V, which limits a low supply-voltage operation below 1 V, Co nversely, in the proposed BGR circuit, V-ref has been converted From the su m of two currents; one is proportional to V-f and the other is proportional to V-T. An experimental BGR circuit, which is simply composed of a CMOS op -amp, diodes, and resistors, has been fabricated in a conventional 0.4-mu m flash memory process. Measured V-ref is 518 +/- 15 mV (3 sigma) for 23 sam ples on the same wafer at 27-125 degrees C.