Patent ID: 7230499
Filing Date: 2007-06-12
Classification: H03K

Abstract:
1. A method to achieve ground noise insensitivity and a constant duty-cycle of chain ring oscillators over temperature and process variations is comprising: provide a chain ring oscillator having n-stages and a clocked means to remove noise from clock pulses; select the output of a stage of the ring oscillator wherein such a phase shift between said stage and the nth stage exists that a subtraction of both outputs eliminates any duty cycle variations due to process and temperature variations; generate a signal being the result of a subtraction of the output of the stage selected in the previous step from the output of the nth stage; clock with the signal generated in the previous step a means to remove noise from clock pulses from the output of the nth stage of the ring oscillator; and buffer the signal, after noise has been removed in the previous step, to provide the final clock signal of the ring oscillator.