A Curvature Compensation Technique for Low-Voltage Bandgap Reference

Abstract

Based on the standard 40 nm Complementary Metal Oxide Semiconductor (CMOS) process, a curvature compensation technique is proposed. Two low-voltage, low-power, high-precision bandgap voltage reference circuits are designed at a 1.2 V power supply. By adding IPTAT (positive temperature coefficient current) and ICTAT (negative temperature coefficient current) to the output resistance, the first-order compensation bandgap voltages can be obtained. Meanwhile, the third high-order compensation current is also superimposed on the same resistance. We make use of the collector current of the bipolar transistor to compensate for the nonlinear term of VBE. The simulation results show that TC (temperature coefficient) of the first circuit reference could be reduced from 29.1 × 10−6/°C to 5.71 × 10−6/°C over the temperature range of −25 to 125 °C after temperature compensation. The second one could be reduced from 17 × 10−6/°C to 5.22 × 10−6/°C.

Keywords

• bandgap reference
• curvature compensation
• nonlinear current