System and method for correcting offset voltage errors within a band gap circuit

A band gap circuit with offset voltage error correction, comprising:

• a diode junction circuit comprising an input node, a first feedback node and a second feedback node, wherein said diode junction circuit comprises proportional and complimentary temperature coefficients when said first and second feedback nodes are driven to a common voltage level;
• an error amplifier having a positive input coupled to said second feedback node, having a negative input coupled to said first feedback node, having an output, and having at least one trim node;
• a current device having a control terminal coupled to said output of said error amplifier and having an output that provides a control current during a normal mode;
• a bias current generator with constant gain that sinks a first bias current and that sources a second bias current;
• a calibration circuit that monitors said output of said current device while adjusting a trim current provided to said at least one trim node of said error amplifier to minimize an offset voltage error of said error amplifier during a calibration mode;
• and
• a mode control circuit that couples said current device to said input node to provide said control current to said diode junction circuit during said normal mode, and that periodically enters said calibration mode during which said mode control circuit decouples said current device from said diode junction circuit, shorts together said positive and negative inputs of said error amplifier, and couples said current generator to sink said first bias current from said output of said current device and to source said second bias current to said input node of said diode junction circuit.