A system and method for converting an analog signal to a digital signal is disclosed. The system includes a multiphase oscillator preferable a rotary oscillator, a sample and hold circuit, an integrator and a time-to-digital converter. The multiphase oscillator has a plurality of phases that are used in the time-to-digital converter to measure the time of a pulse created by the integrator. The edges of the pulse may optionally be sharpened by passing the pulse through a non-linear transmission line to improve the accuracy of the measurement process. To cut down on noise a tuned power network provides power to the switching devices of the rotary oscillator. Calibration is performed by fragmenting the sample and hold circuit and integrator and performing a closed loop calibration cycle on one of the fragments while the other fragments are joined together for the normal operation of the sample and hold and integrator circuits.