Patent ID: 8073092
Filing Date: 2011-12-06
Classification: H03L

Abstract:
1. An integrated circuit device having an internal clock oscillator that is synchronized to an external frequency reference, said integrated circuit device comprising: a digital processor; a clock oscillator supplying a clock signal to the digital processor; a counter having a clock input coupled to the clock oscillator, wherein the counter counts periods of the clock oscillator; a frequency adjustment controller having a count input, a reference count input, an external frequency reference input, a reset output, a frequency increment output, a frequency decrement output, and a disable input for enabling and disabling operation thereof coupled to the digital processor; and an oscillator tuning circuit, the oscillator tuning circuit having frequency increase and decrease inputs coupled to the frequency increment and decrement outputs, respectively, of the frequency adjustment controller; the oscillator tuning circuit is coupled to the clock oscillator, wherein the clock oscillator frequency is determined by the oscillator tuning circuit; wherein the frequency adjustment controller compares the count from the counter with a reference count at the reference count input when a reference frequency period is finished, the reference frequency period is from an external frequency reference coupled to the external frequency reference input of the frequency adjustment controller, and the frequency of the clock oscillator is greater than the frequency of the external frequency reference; wherein: