A method for making the comparison between a continuous value analogue signal and a continuous value digital signal, characterized in that it provides the following steps: - defining a ramp analogue signal (RAMP) having linearly variable value over time, said definition providing to periodically vary, for each time interval belonging to first predetermined time intervals, a first digital numerical value by a predetermined quantity, and providing to convert said first digital numerical value into said ramp analogue signal (RAMP) by means of a digital/analogue converter; - simultaneously comparing, at each of said first predetermined time intervals, the value of said ramp analogue signal (RAMP) with said analogue signal and said first digital numerical value with said digital signal; - verifying at which of said first predetermined time intervals said value of said ramp analogue signal (RAMP) equals said analogue signal and at which of said predetermined time intervals said first digital numerical value equals said digital signal; - temporally defining which of said equalities occurs first and which occurs second and also defining the time window (WIND) between said first equality and said second equality; - increasing a second digital numerical value within said time window (WIND) for each time interval belonging to second predetermined time intervals, said second digital numerical value representing the deviation between said analogue signal and said digital signal; - comparing, at each of said second time intervals, said second digital numerical value with a predetermined threshold value (DELTA) so as to verify if and when said second digital numerical value equals said predetermined threshold (DELTA). - defining a ramp analogue signal (RAMP) having linearly variable value over time, said definition providing to periodically vary, for each time interval belonging to first predetermined time intervals, a first digital numerical value by a predetermined quantity, and providing to convert said first digital numerical value into said ramp analogue signal (RAMP) by means of a digital/analogue converter; - simultaneously comparing, at each of said first predetermined time intervals, the value of said ramp analogue signal (RAMP) with said analogue signal and said first digital numerical value with said digital signal; - verifying at which of said first predetermined time intervals said value of said ramp analogue signal (RAMP) equals said analogue signal and at which of said predetermined time intervals said first digital numerical value equals said digital signal; - temporally defining which of said equalities occurs first and which occurs second and also defining the time window (WIND) between said first equality and said second equality; - increasing a second digital numerical value within said time window (WIND) for each time interval belonging to second predetermined time intervals, said second digital numerical value representing the deviation between said analogue signal and said digital signal; - comparing, at each of said second time intervals, said second digital numerical value with a predetermined threshold value (DELTA) so as to verify if and when said second digital numerical value equals said predetermined threshold (DELTA).