A new curvature-corrected voltage reference based on the weight difference of gate-source voltages for subthreshold-operated MOS transistors

A new curvature-correction technique for improving the temperature behavior of a CMOS voltage reference is presented. The reducing of the temperature coefficient of the reference voltage is realized compensating the nonlinear temperature dependence of the gate-source voltage for a MOS transistor working in weak inversion with the difference between two gate-source voltages. These MOS transistors are polarized at drain currents with different temperature dependencies (PTAT and PTAT2, respectively). The PTAT voltage generator was implemented using an original offset voltage follower block, with the advantage that matched transistors and, in consequence, with a relatively smaller degradation of the circuit temperature behavior caused by devices' mismatches. SPICE simulation reports TC= 1.95 ppm/K for an extended temperature range, 273K < T < 363K, without considering the parameters spread.