A One-Point-Trimmed 18.4 ppm/°C On-Chip Oscillator with Capacitively-Biased-Diode-based Quasi-Digital Temperature Compensation

On-chip oscillators are suitable for low-cost and compact IoT applications, but their temperature stability is relatively poor. This paper presents a temperature compensation technique to improve the stability of an on-chip digitally-controlled oscillator (DCO). The oscillation period of the DCO and the local temperature are simultaneously extracted by a capacitively-biased-diode sensor operating in a code-division-modulation manner. As the period and local temperature readouts are correlated, the proposed technique can achieve accurate temperature compensation despite of voltage variations. With a single-point trim, the proposed oscillator achieves a temperature stability of 18.4 ppm/°C and a voltage stability of 0.24%/V. It consumes a power consumption of 231 μW at an oscillation frequency of 20 MHz.