A Novel 22.7 ppm/0C Voltage mode Sub-Bandgap Reference with robust startup nature

This paper proposes a voltage-mode CMOS bandgap reference circuit. Conventionally in current mode bandgaps, PTAT current generated in bandgap core is added with CTAT current generated using resistor across CTAT voltage to give a constant current. The resistor typically is high and occupies significant area. Further, this leads to multiple operating points and, therefore designing a reliable startup for the current mode bandgap is challenging. The proposed bandgap is designed by giving a fraction of the CTAT voltage to the base of BJT. This eliminates the use of resistor to generate CTAT current and has only 2 stable operating points. A prototype designed in 45nm TSMC CMOS technology for a nominal voltage of 450mV demonstrates 22.7 ppm/°C temperature coefficient from -40^o C to 125^oC, draws 11.8µA from a 1.05Vsupply.