A temperature compensated CMOS relaxation oscillator for low power applications

The design of an area-efficient CMOS relaxation oscillator for low power applications is described. Its architecture includes a temperature compensation scheme based on the matching of bias current circuit and oscillator inverters threshold voltages that provides a clock frequency stable over the entire temperature range (-40°C~125°C). The circuit is the auto-wakeup IP core of a microcontroller family for consumer applications, occupies an area of 0.03mm2 in a 0.5μm CMOS process, operates from 1.5V to 5.5V, and consumes 800nA.