Patent ID: 8344918

Claim:
A process to insert a random noise in a time to digital converter designed to calculate a phase error between a high frequency first signal with respect to a reference second signal, switching at a lower frequency, said process comprising: processing the first signal F DCO by using a chain of delays having a set of n elementary delays which number n is chosen so as to extend over a full period of said first signal; storing outputs of said chain of delays in a set of latches and generating a thermometer code presenting a stream of 1s separated from a stream of 0s by a border corresponding to a transition of said first signal with respect to the second reference signal; reducing said thermometer code by a random number of bits; processing result in an edge detecting and thermometer code decoding so as to generate two variables Δt r and Δt f , the variable Δt r being representative of a difference between a rise time of said first signal with respect to a rise time the second signal and the variable Δt f being representative of a difference between a fall time of said first signal with respect to a fall time of the second signal; computing a normalized gain so as to generate an average value of 1/T DCO , wherein T DCO is a period of said first signal; adding to a value Δt r a binary value corresponding to the random number of bits; and multiplying a preceding result by an average value of 1/T DCO and computing a phase error between the first and second signals.