DTMOST low-voltage reference circuit with logarithmic curvature-correction

A low-power low-voltage bandgap reference using MOS transistors operating in subthreshold region will be presented. In order to decrease the relatively large value of the temperature coefficient for a first-order compensated voltage reference, a new logarithmic curvature-correction technique based on the difference between two gate-source voltages of transistors working at drain currents with different temperature dependencies will be described. The low-voltage operation is achieved by a virtual reduction of V_T using a DTMOST. The circuit was implemented in 0.35 μm CMOS technology on a die area of 50 μm x 60 μm. The experimental results show a temperature coefficient of the circuit of about 6.1 ppm/K for an extended temperature range, 223Kcc =1.8V.