A 2.2μW 600kHz Frequency-Locked Relaxation Oscillator with 0.046%/V Voltage and 48.69ppm/°C Temperature Stability for IoT Sensor Node Applications

This brief presents a 600kHz relaxation oscillator with 2.2 μW power consumption. A low power frequency-locked loop (FLL) structure is proposed to increase the frequency immunity against voltage, temperature and process (PVT) variations. A front-end regulator is proposed to further enhance the voltage stability with limited power overhead. A current-injection scheme is proposed to compensate the temperature variation from the on-chip poly-resistors. Fabricated in 0.18 μm technology, this oscillator can operate at an unregulated supply from 1.1V to 3.3V with 0.046%/V voltage stability and the measured temperature stability is 48.69ppm/°C from -45°C to 125 °C. The measured Jitter rms is 1.56ns with 120k hits.