An embedded temperature-compensated ring oscillator with all-MOS for microcontroller units

Abstract

This paper presents an all-MOS ring oscillator with a temperature compensation circuit, which can be integrated into a microcontroller unit (MCU) chip. We suppose a compensation circuit to mitigate the frequency drift caused by temperature fluctuations. The absence of resistors and capacitors in the oscillator can significantly reduce the layout area. In addition, the current-starved circuit minimizes power consumption and enabls flexible frequency adjustment. The design has been simulated using a 180 nm CMOS process, resulting in a layout area of the oscillator less than 0.00495 mm². Experimental results also demonstrate that the oscillator achieves a stable clock of 350 MHz at a voltage-controlled input of 850 mV. Furthermore, across the temperature range of -40°C to 125°C, the maximum frequency variation remains between -0.88% to +0.297%. The oscillator’s power consumption is as low as 0.315 mW.