Bandgap Voltage Reference for IoT and Wearable Devices Application

Abstract

The Bandgap reference (BGR), which is an important building block such as voltage regulator and data converters, should provide an accurate and stable voltage reference as the temperature and supply variation while consumes as low power as possible. Due to the power limitation, the development trend of the BGR design is to reduce the current consumption and the minimum supply voltage level while proving a fair temperature coefficient (TC) and line regulation (LNR). In this project, a 40-ppm/oC, 40nW, 0.5V supply voltage BGR circuit combined with a switch capacitor network (SCN) is designed in a standard 65nm CMOS technology and has a total core area of 0.052 mm2. The design employed a 2x charge pump to reduce the minimum supply voltage requirement, a proportional to absolute temperature (PTAT) current generator to improve the linearity of the BJT, and the SCN employed a low current leakage design to generate a voltage reference. With a 3-bit trimming circuit, the temperature coefficient of 40 ppm/°C in the range of -40°C - 120°C can be achieved. Compared with the state-of-the-art works, this design can achieve a good TC for a wide temperature range under the low voltage and low power supply condition. The designed BGR is suitable for IoT and wearable devices application as it can provide an accurate and stable reference voltage to the mixed-signal circuit such as sensors, data converter, and voltage regulators. Key words: Bandgap reference (BGR) circuits, CMOS analog integrated circuits, low voltage, low power, temperature coefficient.