A 6.1-nW, 4.3-kHz, -40-90°C Relaxation Oscillator for IoT Applications

This paper proposed a relaxation oscillator (RxO) with an extended operating range achieved through the implementation of a subthreshold leakage current compensation (SLC) technique. The compensated RxO outperforms the uncompensated counterpart by 25 times for temperature coefficient (TC). Moreover, its performance is further optimized using a forward body bias (FBB) technique, resulting in a 30% delay reduction for the buffer at low supply voltage. Designed in a 65nm CMOS process, the proposed RxO consumes 6.1 nW under a 0.4 V supply at 4.3 kHz, achieving an energy efficiency of 1.42 nW/kHz at room temperature. The oscillator exhibits TC of 100.4 ppm/°C across a temperature range from -40°C to 90°C, making it a prospective choice for low-power Internet of Things (IoT) applications.