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.
Highlights
Reference voltage source circuit is an important unit module in integrated circuit design, which is widely used in analog integrated circuits, digital integrated circuits, and hybrid integrated circuits
The high-order temperature compensation circuit in Figure 3 is composed of a resistor, five Negative-Positive-Negative (NPN) bipolar transistors, and three PMOSFETs; two PMOSFETs were removed from the circuit in Figure 4 in order to obtain the opposite compensation
Compensation; (b) 200 Monte Carlo simulation results for TC after high-order temperature compensation
Summary
Reference voltage source circuit is an important unit module in integrated circuit design, which is widely used in analog integrated circuits, digital integrated circuits, and hybrid integrated circuits. In order to reduce the temperature coefficient and improve the precision, many curvature compensation techniques have been presented. The low-voltage reference is generated by the sum of two currents, IPTAT and ICTAT, multiplied by the output resistor. The temperature coefficient of the bandgap source after first-order compensation will not be small, especially in low-voltage structure, the voltage deviation will be amplified, and we will obtain a worse temperature coefficient, usually more than 30 × 10−6 /◦ C. The low-voltage reference is generated by three currents, namely, IPTAT , ICTAT, and INL, that are multiplied by the output resistor. IPTAT is produced from ∆VBE, Energies 2021, 14, x FOR PEER REVIEW and ICTAT is produced from VBE The sum of these two opposite TC currents can present two typical curves, a convex curve, and a concave curve. When the reference convex curve, the second of its is nonlinear current forms acurrent convexforms curve,athe second derivative of itsderivative nonlinear term less thanterm zero.is than Izero
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