Ultra low power, trimless and resistor-less bandgap voltage reference

Abstract

A trimless and ultra low power bandgap voltage reference circuit is proposed. The proposed circuit topology replaces the resistors of conventional bandgap voltage reference circuit with stack of MOSFET, which results in improvements in area and power consumption. Process invariability is achieved by tapping reference voltage output at different accessible nodes in a MOSFET stack. This topology avoids the inevitable post-fabrication trimming cycle. The presented bandgap voltage reference circuit is analyzed theoretically and compared with other existing similar architectures. The circuit is designed and simulated in standard 180 nm mixed-mode CMOS technology which gives a reference level of 990 mV. The minimum required supply voltage is 1.5 V with maximum current drawn of 23 nA. A temperature coefficient of 24 ppm/°C is obtained over -25°C to 125°C temperature range. Facility of tapping the reference voltage at different nodes in MOSFET stack nullifies the process variations and gives the worst case accuracy up to 25 ppm/°C. Presented reference circuit gives the supply regulation of 7.25 mV/V with area consumption of 300μ m 170μ m.