Fast synchronization of a number of digital clocks

1. A method for synchronizing a plurality of digital clocks to a synchronizing signal, said method comprising:

generating centrally a reference clock;

synthesizing, from said reference clock using a first clock multiplier, a first digital clock, wherein said first clock multiplier includes:

(a) a phase locked loop having a divider that is programmable to provide a first divider ratio so that said first digital clock has a first frequency, wherein said first clock multiplier has a first settling time, and

(b) a first masking circuit that, in response to said synchronizing signal, generates a first time delay signal that masks an output of said first clock multiplier for a period of time that is at least as long as said first settling time;

synthesizing, from said reference clock using a second clock multiplier, a second digital clock, wherein said second clock multiplier includes:

(a) a phase locked loop having a divider that is programmable to provide a second divider ratio so that said second digital clock has a second frequency, wherein said second clock multiplier has a second settling time, and

(b) a second masking circuit that, in response to said synchronizing signal, generates a second time delay signal that masks an output of said second clock multiplier for a period of time that is at least as long as said second settling time; and

in response to a receipt of said synchronizing signal:

(i) resetting said first and second clock multipliers; and

(ii) generating said first and second time delay signals, thus masking said output of said first clock multiplier during said first settling time, and masking said output of said second clock multiplier during said second settling time.

2. The method of claim 1 , further comprising synchronizing said synchronizing signal to said reference clock.

3. The method of claim 2 , wherein said synchronizing signal is synchronized centrally to said reference clock, and said synchronizing signal and said reference clock are distributed to a plurality of electronic circuits synthesizing one of said plurality of digital clocks, respectively.

4. The method of claim 1 , wherein said first clock multiplier further comprises an additional divider coupled in series to said phase locked loop of said first clock multiplier.

5. The method of claim 4 , wherein said additional divider is reset in response to said synchronizing signal.

6. The method of claim 4 , further comprising counting, by a first counter, in response to said synchronizing signal, an output signal of said first divider, or said reference clock, wherein said first counter provides said first time delay.

7. The method of claim 6 , further comprising counting, by a second counter, an output of said phase locked loop of said first clock multiplier, wherein said second counter starts counting in response to an output signal of said first counter, said second counter providing a delay time for a common synchronization of at least some of said plurality of digital clocks.

8. The method of claim 5 , further comprising counting, by a first counter, in response to said synchronizing signal an output signal of said first divider, or said reference clock, wherein said first counter provides said first delay time.

9. The method of claim 8 , further comprising counting, by a second counter, an output of said phase locked loop of said first clock multiplier, wherein said second counter starts counting in response to an output signal of said first counter, said second counter providing a delay time for a common synchronization of at least some of said plurality of digital clocks.

10. A storage medium having a program encoded thereon that is executable in a processor to perform a method that includes:

generating centrally a reference clock;

synthesizing, from said reference clock using a first clock multiplier, a first digital clock, wherein said first clock multiplier includes:

(a) a phase locked loop having a divider that is programmable to provide a first divider ratio so that said first digital clock has a first frequency, wherein said first clock multiplier has a first settling time, and

(b) a first masking module that, in response to said synchronizing signal, generates a first time delay signal that masks an output of said first clock multiplier for a period of time that is at least as long as said first settling time;

synthesizing, from said reference clock using a second clock multiplier, a second digital clock, wherein said second clock multiplier includes:

(a) a phase locked loop having a divider that is programmable to provide a second divider ratio so that said second digital clock has a second frequency, wherein said second clock multiplier has a second settling time, and

(b) a second masking module that, in response to said synchronizing signal, generates a second time delay signal that masks an output of said second clock multiplier for a period of time that is at least as long as said second settling time; and

in response to a receipt of said synchronizing signal:

(i) resetting said first and second clock multipliers; and

(ii) generating said first and second time delay signals, thus masking said output of said first clock multiplier during said first settling time, and masking said output of said second clock multiplier during said second settling time.

11. A system for synchronizing a number of digital clocks to a synchronizing signal, said system comprising:

a generator that generates centrally a reference clock;

a first synthesizer that synthesizes a first digital clock from said reference clock using a first clock multiplier, wherein said first clock multiplier includes:

(a) a phase locked loop having a divider that is programmable to provide a first divider ratio so that said first digital clock has a first frequency, wherein said first clock multiplier has a first settling time, and

(b) a first masking circuit that, in response to said synchronizing signal, generates a first time delay signal that masks an output of said first clock multiplier for a period of time that is at least as long as said first settling time;

a second synthesizer that synthesizes a second digital clock from said reference clock using a second clock multiplier, wherein said second clock multiplier includes:

(a) a phase locked loop having a divider that is programmable to provide a second divider ratio so that said second digital clock has a second frequency, wherein said second clock multiplier has a second settling time, and

(b) a second masking circuit that, in response to said synchronizing signal, generates a second time delay signal that masks an output of said second clock multiplier for a period of time that is at least as long as said second settling time; and

wherein said first clock multiplier, in response to a receipt of said synchronizing signal:

(i) resets said first clock multiplier; and

(ii) generates said first time delay signal, thus masking said output of said first clock multiplier during said first settling time, and

wherein said second clock multiplier, in response to a receipt of said synchronizing signal:

(i) resets said second clock multiplier; and

(ii) generates said second time delay signal, thus masking said output of said second clock multiplier during said second settling time.

12. The method of claim 1 , further comprising keeping said first divider ratio constant while said first time delay signal is active.

13. The method of claim 12 , further comprising dynamically varying said first divider ratio, after said first time delay signal goes inactive.

14. The storage medium of claim 10 , wherein said method further includes keeping said first divider ratio constant while said first time delay signal is active.

15. The storage medium of claim 14 , wherein said method further includes dynamically varying said first divider ratio, after said first time delay signal goes inactive.

16. The system of claim 11 , wherein said system keeps said first divider ratio constant while said first time delay signal is active.

17. The system of claim 16 , wherein said system dynamically varies said first divider ratio, after said first time delay signal goes inactive.