A digitally corrected bandgap voltage reference with a 3σ temperature coefficient of 3.8 ppm/K

Abstract

Bangap voltage references (BGRs) are widely used in today's circuits as references with a low temperature coefficient. Especially measurement circuits and metering applications demand a very low temperature coefficient to maintain the desired precision over the entire temperature range. Today's BGR designs use analog circuits to correct for the effects which lead to a temperature drift. In this paper a bandgap reference voltage which uses a digital correction technique is presented. The proposed design includes a temperature sensor to measure the current chip temperature and a bandgap reference which is controllable by a 3-bit digital input. The input to the bandgap block is calculated using a digital correction algorithm. The proposed design was implemented in a 0.35 μm CMOS process and occupies 0.437 mm2. After calibration, a 3σ temperature coefficient of 3.8 ppm/K is achieved over a temperature range from -40°C to 100 °C. With the proposed design, high performance measurements over a large temperature range have become possible. The digital design allows for an easy adaptation to various needs and temperature coefficients.