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

Abstract

This paper proposes a CMOS bandgap reference (BGR) circuit, which can successfully operate with sub-1-V supply, In the conventional BGR circuit, the output voltage V/sub ref/ is the sum of the built-in voltage of the diode V/sub f/ and the thermal voltage V/sub T/ of kT/q multiplied by a constant. Therefore, V/sub ref/ is about 1.25 V, which limits a low supply-voltage operation below 1 V. Conversely, in the proposed BGR circuit, V/sub ref/ has been converted from the sum of two currents; one is proportional to V/sub f/ and the other is proportional to V/sub 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-/spl mu/m flash memory process. Measured V/sub ref/ is 518/spl plusmn/15 mV (3/spl sigma/) for 23 samples on the same wafer at 27-125/spl deg/C.