Zero-Order Curvature-Corrected Voltage References
Presenting the advantage of simplicity, zero-order curvature-corrected voltage reference circuits exhibit a relatively large value of the temperature coefficient. For bipolar technology, base–emitter voltage and Zener voltage represent the most common approach for designing CTAT voltage references; the difference between two base–emitter voltages being the usual method for implementing PTAT voltage references. The CMOS technology offers the possibility of implementing a CTAT voltage starting from the gate–source voltage or from the threshold voltage, while the PTAT voltage references exploit the difference of two gate–source voltages for subthreshold-operated MOS devices. The area of application for zero-order curvature-corrected voltage reference is related to the basic circuits that not require a very small value of the temperature coefficient, representing, also, the basis from developing first-order and superior-order curvature-corrected voltage references with a much better temperature behavior. Additionally, PTAT voltage references could be used as absolute temperature sensors in the hypothesis of a high linearity of their temperature dependence.