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.