US Patent 10108148 Time to digital converter with increased range and sensitivity

Systems and methods are provided for converting time measurements to digital value representing phase. Such systems and methods use a ring oscillator to create a coarse measurement of the time difference between first and second rising edges of a modulated signal. A two-dimensional Vernier structure is used to create a fine resolution measurement of the error in the coarse measurement. The coarse and fine measurements are combined to calculate a digital time measurement. A digital time output is calculated as the difference in successive digital time measurements. An offset digital time output is calculated as a difference in a digital time output in relation to a carrier period offset. The offset digital time output is scaled and accumulated to calculate the integrated time signal. The integrated time signals are synchronized to the carrier frequency to output a series of final phase measurements.