It is possible to digitize relatively long time intervals by incrementing a counter with a repetitive signal derived from an oscillator. For short time intervals the time-to-digital converter (TDC) circuit shown in figure 8.8 can be used.
Figure 8.8: A time-to-digital converter. The circuit is shown with the switches in the signal-holding position after a STOP pulse and with RESET false.
The resulting voltage on the capacitor is proportional to the time between the START and STOP pulses as shown in figure 8.9.
Figure 8.9: TDC timing signals.