A 40.6 ppm/°C 368 nW 10 kHz Relaxation Oscillator with Temperature-Sensor-based Piece-Wise Compensation Technique

This paper proposes an on-chip 10kHz relaxation oscillator (RxO) for Internet-of- Things (IoT) application. To reduce the frequency temperature coefficient (TC) of the RxO, a novel temperature-sensor-based piece-wise compensation scheme is introduced, which employs different hybrid resistor network combination for the proposed RxO according to the ambient temperature variation. Furthermore, a capacitance calibration method is employed to compensate the frequency drift caused by the process variation. The circuit is designed and simulated in a 0.18
$\boldsymbol{\mu}\mathbf{m}$
CMOS process. The proposed RxO acquires a frequency temperature coefficient of 40.6 ppm/°C from −40°C to 125 °C with the frequency drift of −0.41% to 0.26%. The frequency variation is 0.459% at the supply from 0.95 V to 2 V, and the typical power consumption is 368 nW under a supply voltage of 1 V.