A Picowatt CMOS Voltage Reference Using Independent TC and Output Level Calibrations

We propose a low-power voltage reference that enables independent adjustment of temperature sensitivity and output level. This design enhances the temperature sensitivity without impacting the output level distribution, in contrast to previous methods. The proposed circuit achieves this by integrating a separate control system that utilizes diode-connected pMOS transistors and an analog multiplexer for output level adjustment, along with biasing current control to improve the temperature sensitivity. In a 180-nm CMOS process, the prototype circuit generates a stable reference voltage averaging 192 mV, maintaining an accuracy of ±8.8 mV (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pm 3\sigma $ </tex-math></inline-formula>) from 0 °C to 75 °C across ten samples. In addition, it consumes only 35.8 pW at 0.6 V and 25 °C.