3.1 A PVT-Insensitive Sub-Ranging Current Reference Achieving 11.4ppm/°C from −20°C to 125°C

Improving the temperature stability of the reference current (I <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">REF</inf> ) is essential for the reliable operation of precision electronics for various applications, including automotive and industrial sensors. There are several approaches to generate a temperature-stable I <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">REF</inf> , which include a weighted sum of PTAT and CTAT currents, dividing a reference voltage by a resistor with a similar temperature coefficient (TC) [1–3], and biasing a MOSFET at its zero-temperature-coefficient bias point [4]. While these techniques can remove the first-order TC, the remaining curvature due to the second-order TC limits the achievable temperature stability. In [5], the curvature in a reference current is corrected by using a curvature-corrected bandgap reference voltage and a switched capacitor resistor. However, it requires a stable and bulky reference oscillator (e.g., crystal).