A CMOS band-gap reference circuit with sub 1 V operation

This paper proposes a CMOS band-gap reference (BGR) circuit, which can successfully operate with sub-1 V. In the conventional BGR circuit, the output voltage, Vref, is the sum of the built-in voltage of the diode, Vf, and the thermal voltage, VT, of kT/q multiplied by a constant. Thereby, Vref is about 1.25 V, which limits a low Vcc operation below 1 V. Conversely, in the proposed BGR circuit, Vref has been converted from the sum of two currents; one is proportional to Vf; and the other is proportional to VT. An experimental BGR circuit, which is simply composed of a CMOS opamp, diodes, and resistors, has been fabricated in a conventional double metal 0.4 /spl mu/m process. Measured Vref is 515 mV/spl plusmn/15 mV (3 /spl sigma/) for 23 samples on the same wafer at 27/spl deg/C through 125/spl deg/C.