Compact, very low voltage, temperature-independent reference circuit

A compact, very low voltage, temperature-independent reference circuit, which is based on the thermal properties of bipolar junction transistors in the saturation region is presented. The new circuit operates from a minimum power supply of less than 1V and provides a reference voltage with a nominal thermal drift of ∼30 ppm/°C in the temperature range between −40 and 110°C. The proposed circuit has been integrated on silicon by a 0.35 µm CMOS technology and a reference voltage with a measured untrimmed thermal drift of ∼100 ppm/°C has been reported. The new voltage reference occupies a silicon area of only 3,500 µm2, shows a power consumption of <30 µW and its DC power supply rejection is better than 65 dB.