Patent ID: 6850051

Claim:
A method for measuring a time difference between a first event and a second event, comprising the steps of: triggering a first oscillator circuit to generate a first oscillation signal with an oscillation period T s upon detection of said first event; triggering a second oscillator circuit to generate a second oscillation signal with an oscillation period T f upon detection of said second event, wherein T s is not equal to T f and wherein a difference, ΔT, between T s and T f is small with respect to either of T s and T f ; detecting a change of phase between said first and second oscillation signals; and determining a time difference between said first and said second events from said difference, ΔT, between T s and T f and a count of a number of cycles, N m , of only one of said first oscillator circuit and said second oscillator circuit at which said detected change of phase occurs.