Post-Manufacturing Process and Temperature Calibration of a 2-MHz On-Chip Relaxation Oscillator.

In this work, the design methodology of the relaxation oscillator with the post-processing trimming option for frequency and temperature coefficient is presented. A novel oscillator core is introduced, which ensures good control linearity and insensitivity to CMOS variations of the output frequency as a prerequisite for frequency and temperature calibration. The proposed oscillator operates at 2 MHz and consumes typically about $I_{DD}=97.8\,\,\mu \text{A}$ at the nominal temperature of 42.5°C and nominal supply voltage of $V_{DD}=1.8$ V. The oscillator is verified experimentally with 10 samples manufactured in 180 nm CMOS process, each covering an area of 0.075 mm2. The frequency and temperature calibration was performed based on the two-point temperature measurements, resulting in a significant improvement in frequency stability. The temperature calibrated oscillator has a temperature variation ±0.30% in the temperature range from −40°C to 125°C, and the variation with the power supply ±0.07% in the supply range from 1.62 V to 1.98 V. [ABSTRACT FROM AUTHOR]