Time To Digital Converter - Discriminator

Discriminator

In practice, a TDC usually follows a discriminator.

Even if the input is binary, after sampling with the oscillator signal the signal is analog (due to the finite edge width). Therefore an analog-to-digital converter is always employed after the sampler, the same is true for a simple comparator which can be implemented as a cascade of differential amplifiers, where the latter stages are driven into saturation, that means either into the low or the high state (1-bit ADC). At every leading edge of the time-discrete and voltage-discrete signal the time is fed into the FIFO.