A low-power temperature-compensated relaxation oscillator for built-in test signal generation

Abstract

An on-chip frequency reference for built-in testing and calibration applications is presented. The design combines a proportional-to-absolute-temperature (PTAT) current reference and a relaxation oscillator core. A temperature compensation scheme is realized based on the thermal voltage, for which simulations indicate low sensitivity to process variations. The oscillator was designed and simulated in a 130nm CMOS process with a power supply of 1.2V. It generates a 40KHz output and occupies a layout area of 0.025mm2. A temperature coefficient of 101ppm/°C is achieved over the range from -30°C to 85°C. The simulated phase noise is -90dBc/Hz at 10KHz offset.