Patent ID: 7259543

Claim:
A bandgap reference circuit operating under a voltage source comprising: a first circuit with a first differential amplifier for generating a first current; a second circuit with a second differential amplifier for generating a second current, wherein the first circuit and the second circuit comprise BiCMOS transistors; a start-up circuit for providing an initial current to the first circuit, wherein the start-up circuit further comprises a NMOS transistor and a first PMOS transistor coupled in series with a gate of a second PMOS transistor coupled to drains of the first PMOS transistor and the NMOS transistor; and a bandgap reference voltage output module for combining the first current and the second current to output a bandgap reference voltage, wherein the first current increases while the second current decreases with the increase of temperature, thereby the first circuit and the second circuit complement each other for offsetting variations of the bandgap reference voltage due to temperature changes.