An 143nW relaxation oscillator for ultra-low power biomedical systems

This work presents a near zero power relaxation oscillator for biomedical applications. Relaxation oscillators have now become a potential candidate for on-chip clock references due to their miniaturized sizes and integrating capability. In order to be suitable for biomedical applications, accurate and energyefficient oscillators are required. An ultra-low power relaxation oscillator with 20kHz oscillating frequency is implemented with 0.13μm CMOS process. A switched-current technique is proposed to reduce the power consumption without compromising the overall performance. The relaxation oscillator consumes 143nW power and has a temperature coefficient of 19.1ppm/°C with a phase noise of -93dBc/Hz at 1kHz offset frequency.