An 18-nA Ultra-Low-Current Resistor-less Bandgap Reference for 2.8 V -4.5 V High Voltage Supply Li-ion-Battery-Based LSIs

This brief presents a resistor-less bandgap reference (BGR) with ultra-low current consumption, which can be applied in energy harvesting systems that use lithium-ion (Li-ion) batteries as intermediate energy storage. The system supply voltage is defined by the output voltage of the Li-ion battery, which is usually from 3 V to 4.2 V. The BGR circuit working in this kind of system needs to withstand a high supply voltage while consuming nano-watt power. In this brief, differential pairs are first used in a low-power BGR circuit as a voltage duplicator to achieve duplication of both the proportional-to-absolute-temperature (PTAT) voltage and the trimming network, which can reduce the complexity of the structure and the chip area of the trimming network. The total current consumption of the BGR is around 18 nA for different supply voltages ranging from 2.8 V to 4.5 V. Fabricated in a 0.35- ${\mu }\text{m}$ CMOS process, the BGR circuit generates a 1.17 V bandgap voltage with an average temperature coefficient of 65 ppm/°C and a line regulation of 0.112 %/V.