Design of Low Power Low Temperature Drift Reference Current Source with Startup Circuit

This article addresses the issues of complex and high power consumption in low-temperature drift reference current source circuits, and designs a reference current source with low power consumption, low-temperature drift, and a wide power supply voltage range. The reference current source adopts the temperature characteristics of the $\mathbf{V}_{\mathbf{B}\mathbf{E}}$ and $\triangle\mathbf{V}_{\mathbf{B}\mathbf{E}}$ of the transistor, exhibiting a near zero temperature characteristic. In order to eliminate the two non ideal operating degeneracy points in the circuit, a starting circuit is designed to ensure that the reference current source starts up to normal working state after the power is turned on, while improving the stability of the circuit. The circuit is designed based on 0.18um BCD technology and applied in a soft start circuit of a step-down DC-DC converter. The results show that the circuit proposed in this article outputs a reference current of 2.92uA, a temperature drift coefficient of 182.2ppm/°C, and an overall current consumption of 7.5uA at an input voltage of 2.1-5.5V power supply voltage and a temperature range of -25~125 °C.