Nano-watt 0.3 V supply resistorless voltage reference with Schottky diode

The analysis and design of a resistorless sub-bandgap voltage reference using Schottky diode and Low-V_To transistors is presented herein. The circuit is self-biased and works in the nano-ampere consumption range, achieving full operation at 0.3 V of supply voltage. The design is validated through post-layout simulations including process variability analysis, for a commercial 130 nm CMOS process. A voltage reference of 102.8 mV is reached under V_DD = 1.2V and 92.5 mV for V_DD = 0.3V, with a temperature coefficient (TC) of 215.7 ppm/°C and 216 ppm/°C, respectively using curvature correction to improve the TC in the range from -40° C to 120° C. The current consumption is 212 nA with V_DD = 1.2V at 27°C, and the chip area is 0.0068 mm².