A 12.5-ppm/°C 1.086-nW/kHz Relaxation Oscillator with Clock-Gated Discrete-Time Comparator in 22nm CMOS Technology

This work presents a low-power, low-temperature-coefficient (TC), digital-friendly RC relaxation oscillator (RxO) for energy-constrained Internet-of-Things (IoT) applications. Implemented in a 22nm CMOS technology that offers only PTAT resistors, the proposed swing-adaptive scheme compensates the first-order TC within the RC stage. Additionally, a clock-gated discrete-time comparator (DT-CMP) scheme is adopted to relax the trade-off between power efficiency and TC. The prototype RxO is measured to have a reference frequency of 700kHz with a TC of 12. $5\mathrm{p}\mathrm{p}\mathrm{m}/{}^{\circ}\mathrm{C}$ (from -$40{}^{\circ}\mathrm{C}$ to 85°C), consuming 760nW with a power efficiency of 1.086nW/kHz.