A 100-Hz, 2nW RC Oscillator Using Resistance Amplifier

This paper introduces an ultra-low-power RC oscillator that utilizes a resistance amplification technique. The resistance amplifier achieves the effect of a large resistance by amplifying the I-V characteristics of a small resistance, resulting in significant area savings. To improve precision in oscillation frequency, a continuous time auto-zeroing technique is incorporated to dynamically calibrate the offset voltage of an integrated amplifier. Fabricated using a $180-\mathrm{nm}$ CMOS process, the designed oscillator produces a $100-\mathrm{Hz}$ clock signal while consuming only 2 nW power under compact silicon area $\left(0.12 \mathbf{m m}^{2}\right)$. Additionally, it achieves a competitive temperature coefficient (TC) of $280 \mathrm{ppm} /{ }^{\circ} \mathrm{C}$ and line sensitivity (LS) of 1.1 % / V without the need for any calibration.