A nano-power sub-bandgap voltage and current reference topology with no amplifier

Abstract

A sub-bandgap current and voltage reference operating at ultra-low quiescent current is proposed for energy harvesting and battery-operated systems. Using a single bipolar junction transistor (BJT) and no operational amplifier (opamp), the current reference is generated from proportional-to-absolute-temperature (PTAT) and complementary-to-absolute-temperature (CTAT) voltages combined in a simple three-branch self-biased structure, while the voltage reference is derived by driving the current reference to a temperature-insensitive resistor. The line sensitivity (LS) is enhanced by incorporating cascode devices into the original configuration. Designed in a 0.18-µm standard CMOS process, the proposed architecture occupies an active area of 609 µm × 755 µm with around 47 nA current consumption regardless of temperature. The generated current and voltage references are 6.7 nA and 180 mV, and their temperature coefficients (TC) are 32.76 ppm/°C and 34.80 ppm/°C across the temperature range from −40 to 120 °C, respectively. The minimum supply voltage is 1.1 V, and the line sensitivity of the voltage and current reference are 0.031%/V and 0.03%/V, respectively, over the supply voltage range of 1.1–1.8 V.