A 120nW, 121 kHz, -20~100°C CMOS Relaxation Oscillator with Digital Current Comparator and On-Chip Voltage and Current Reference

A relaxation oscillator(RO) composed of a voltage and current reference (VCR) and a digital current comparator is presented in this paper. By using two different types of resistors with opposite temperature coefficient (TC) in the VCR, this design successfully stabilizes the operation frequency from -20 to 100° C with a very simple structure. Designed in a standard 180nm CMOS process, the proposed RO consumes 120nW under a 0.8V supply and operates at 121kHz, with a TC as low as 36.2 ppm/°C.