CMOS bandgap voltage reference

Year	Description
1998	Invention patented by Bruce W. McNeill and Robert W. Walden on August 27th, 1998. Abstract: A bandgap voltage reference circuit for 0.35-.mu.m, 3-volt CMOS technology operates in an essentially temperature independent manner and having low supply voltages. The bandgap voltage reference circuit incorporates two operational amplifiers. One operational amplifier biases bipolar devices of the circuit and generates a PTAT voltage across a resistor, and the other operational amplifier buffers a voltage related to the PTAT voltage and a voltage across one bipolar device to generate the bandgap voltage reference. In one embodiment, the circuit includes a start-up circuit to ensure a stable and desired start-up state. A current bias may also be provided. The bandgap voltage reference of the second operational amplifier may also provide a regulated supply for the first stage of the circuit. The second operational amplifier also provides a buffered output to a resistor divider circuit to supply a voltage divider to generate voltages below the 1.24-volt bandgap voltage. The bandgap voltage reference circuit includes two versions, one which is optimized for a low supply voltage potential V.sub.DD of approximately 1.8 volts and the other for a standard supply voltage V.sub.DD of approximately 2.4 volts.
Source: selected by the editor from original sources.

Invention: CMOS bandgap voltage reference