All-CMOS subbandgap reference circuit operating at low supply voltage

This paper presents a CMOS subbandgap reference circuit operating at a low supply voltage. To support low-voltage operation, the subbandgap reference circuit uses nMOS transistors operating in weak inversion and a bulk-driven amplifier. Measurements of a chip fabricated in AMI 0.5 μm CMOS technology show that the subbandgap reference can operate with a 1 V supply voltage to produce a reference voltage of 337 mV with a temperature coefficient of 9.9 ppm/°C and a voltage coefficient of 290 ppm/V over the temperature range of 10 °C to 100°C. Measurements of a chip fabricated in UMC 0.13 μm CMOS technology indicate the capability of operation with a 0.4 V supply voltage.