US Patent 10122378 Digital-to-time converter and operating method thereof

A digital-to-time converter includes: a digital-to-analog converter configured to generate a precharge voltage corresponding to a value of a digital code; a ramp generator configured to precharge a capacitor connected to a first node based on the precharge voltage, and to charge or discharge the capacitor based on a reference current provided from a current source in response to a transition of an input clock signal to generate a ramp voltage in the first node; and a comparator configured to generate an output clock signal based on the ramp voltage, wherein the ramp generator includes: a first switching circuit configured to provide a first current path between a second node connected to the current source and the first node; and a second switching circuit configured to provide a second current path from a power supply voltage source to the second node.