US Patent 7636010 Process independent curvature compensation scheme for bandgap reference

In a voltage reference circuit, a bandgap reference circuit, for generating a bandgap reference voltage and a reference current, includes an operation amplifier, and a first transistor for providing the reference current. Another transistor mirrors the reference current to provide a first current. A compensation controller converts a node voltage from the bandgap reference circuit into a second current and performs current subtraction on the first current and the second current to provide a compensation feedback current to another node of the bandgap reference circuit. So that, second order temperature compensation is performed on the bandgap reference voltage.