A 0.5-V Supply, 36 nW Bandgap Reference With 42 ppm/°C Average Temperature Coefficient Within-40 °C to 120 °C

This paper presents a switched capacitor network (SCN)-based bandgap voltage reference (BGR) circuit designed and implemented in a 65nm standard CMOS process with a wide temperature range, high precision, low supply voltage and low power consumption for IoT device application. The proposed BGR employs a 2x charge pump with ripple optimization design to supply the VEB generator, which can relax VDD from 0.9V to 0.5V.A proportional to absolute temperature (PTAT) current source is proposed to bias the PNP BJT in order to reduce the nonlinearity of VEB. Moreover, a voltage divider SCN with low leakage consideration to form the complementary to absolute temperature (CTAT) voltage is designed to reduce the nonlinearity of its coefficient, while a series-parallel SCN with adjusted clock swing to form the PTAT voltage is designed to improve the line regulation of the BGR. The measurement result shows that the proposed BGR has a temperature coefficient (TC) of 42 ppm/degrees C at 0.5V supply within - 40 degrees C to 120 degrees C. The line regulation is 3.2mV/V or 0.64%/V from 0.5V to 1V. Based on 6-chip test result, it shows a 3 degrees / mu variation of 3.08% before trimming, while 0.36% after trimming.