A 870 ppm/V 53 ppm °C 7 MHz Non-Trimmed RC Relaxation Oscillator Using Mixed-Signal Compensation Loop From-40 °C to 165 °C

In this paper, an RC relaxation oscillator exhibiting robust performance over an extended temperature and supply range is proposed. By incorporating a digitally-assisted calibration loop, the design eliminates the errors from switch on-resistance, comparator offset and propagation delay. Fabricated using a 180 nm bipolar-CMOS-DMOS (BCD) process technology, the oscillator operates at a frequency of 7MHz with the supply sensitivity of 870 ppm/V across a voltage range of 1.7 to 4.2 V. The evaluation of 40 untrimmed samples achieved an average temperature coefficient (TC) of 52 ppm/ degrees C from $-$ 40 degrees C to 165 degrees C, with the worst observed TC being 81 ppm/ degrees C. The aging test results indicate small deviations of 0.3% and 11% in the oscillation frequency and its TC, respectively. Furthermore, the direct power injection test confirms its reliability and robustness with a maximum error of oscillation frequency of 6.4%.