A self-calibrating, wide-range temperature sensor includes a current reference, impervious to process and voltage, with the current reference mirrored into two oppositely-sized bipolar transistors or diodes. Duplicate current sources are used with a ratio of geometries between them, such that the larger current biases the smaller bipolar transistor (less cross-sectional area) and the smaller current source biases the larger bipolar transistor (higher cross-sectional area). The current source in conjunction with the differential temperature sensing provides inherent calibration without drift while the differential sensing, from the ratio of geometries in the current paths also increases sensitivity.