A Low Temperature Drift Bandgap Reference Structure Undervoltage Lockout Circuit

To address the issues associated with traditional under-voltage lockout (UVLO) circuits, which rely on external bandgap reference voltage sources and bias currents, and are not conducive to low-power applications due to the inability to turn off the reference source during under-voltage conditions, this paper presents an improved UVLO circuit. The proposed circuit eliminates the need for external reference sources and comparator modules by utilizing a bandgap reference structure to achieve low sensitivity of the hysteresis voltage to temperature and process variations. Additionally, it features high-order temperature compensation, which enhances the reliability and independence of the under-voltage protection circuit. Based on this approach, the circuit was designed and laid out using a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.18\mu M$</tex> BiCMOS process, with a chip area of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$120\mu M\times 80\mu M$</tex>. Simulation results show that at an ambient temperature of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$25^{\circ}C$</tex>, the UVLO has an upper threshold of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$3.8V$</tex>, a lower threshold of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$3. 6V$</tex>, and a hysteresis voltage of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.2V$</tex>. Over a temperature range of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$-40^{\circ}C$</tex> to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$180^{\circ}C$</tex>, the temperature drift of the hysteresis voltage is <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$3mV$</tex>, demonstrating a low temperature drift characteristic.