1. A time to digital converter, comprising: a sampling module configured to sample an input signal at multiple different instances of time; a transition detection module comprising a plurality of comparison elements, each comparison element configured to process the sampled input signal at successive instances of time so as to detect transitions in the input signal in terms of time; an output module comprising multiple parallel outputs with each output operable to output a detection signal indicating a detected transition in the input signal; and a counter circuit for each output of said multiple parallel outputs, wherein a value of each counter circuit is incremented in response to receipt of the detection signal.