ABSTRACT
The analog-to-digital converter (ADC) is one of the most popular devices in electronics, but the time-to-digital converter (TDC) is a not-so-popular device. The TDC has been used mostly in scientific experiments to measure the lifetime of nuclei, the quenching time of fluorescence, the drift time of ions, the time of flight of moving particles, and so on. The TDC digitizes input signal transition time, which is asynchronous to the digitizing system clock. There are various TDC circuits that were proposed and developed. The selection of the circuit depends on the required time resolution, hit rate capability, power consumption, and so on. One of the main applications of the TDC is the distance detection system of automobile and airplanes. Another example is time-of-flight positron emission tomography. The TDC circuit is used as a replacement of an analog circuit in advanced large-scale integrated-circuits processes.
