US Patent 9170564 Time-to-digital converter and PLL circuit using the same

A time-to-digital converter (TDC) that has high resolution, excellent linearity, and a widerange. The TDC includes a first oscillator unit that generates and outputs a pair of first oscillation signals based on a pair of predetermined clock signals that have a predetermined phase difference, a second oscillator unit that generates and outputs a second oscillation signal that have a predetermined frequency based on the pair of first oscillation signals outputted from the first oscillator unit, and a quantizer that calculates a quantized value based on a number of edges of the second oscillation signal outputted from the second oscillator unit.