US Patent 7151403 Adaptive self-calibration method and apparatus

Feedback for self-calibration of any parameter in an analog and/or digital system is described wherein a system quality factor can be represented by a voltage or current differential. The preferred embodiment is operative to alternately supply two or more optimally equivalent currents or voltages from such a system, detect amplitude and/or phase feedback of resultant output signal at the frequency of the alternation, and use feedback to modify a calibration value, voltage, or current so as to minimize or maximize the feedback, thus effecting self-calibration of the system. Such a method and attendant apparatus enables system self-calibration without need of any high-precision or high-cost components.