An apparatus and method for a temperature and calibration utilizing resonant frequency peaks in an oscillator. A circuit providing resonant peaks for utilization for temperature measurements comprising a resonator device for providing an oscillating source, a variable gain-bandwidth amplifier in parallel with the crystal/resonator for providing modulation of the gain and/or bandwidth driving the crystal/resonator, and control of resonant peaks for selection for oscillation, a first capacitor electrically coupled to the parallel combination of the input of the variable gain-bandwidth amplifier, and the resonator device for providing charge storage for oscillation, and a second capacitor electrically coupled to parallel combination of the output of the variable gain-bandwidth amplifier, and the resonator device for providing charge storage for oscillation.