Clock grid for integrated circuit
Systems and methods are provided for distributing clocks or other signals on an integrated circuit. In some aspects, one ore more distributed deskewing objects are provisioned for reducing or eliminating skew while linking multiple clock distribution segments into one clock tree of an arbitrary shape and size.
1. A signal network for distributing clock-type signals in an integrated circuit, said signal network comprising:
a global clock bus;
a plurality of clock regions that intersect one another, wherein the global clock bus is coupled to the plurality of clock regions; and
a switch box located at an intersection of the plurality of clock regions, wherein the switch box comprises a distributed deskew object that:
detects a phase of an input clock signal provided by the global clock bus and a phase of a feedback clock signal; and
generates an adjustable delay based at least in part on the phase of the input clock signal and the phase of the feedback clock signal.
2. The signal network of claim 1 , wherein the distributed deskew object increments or decrements a counter value based at least in part on the phase of the input clock signal and the phase of the feedback clock signal.
3. The signal network of claim 2 , wherein the distributed deskew object generates the adjustable delay proportional to the counter value.
4. The signal network of claim 1 , wherein the distributed deskew object adjusts the feedback clock signal with the adjustable delay.
5. The signal network of claim 4 , wherein a phase of the feedback clock signal adjusted with the adjustable delay is substantially equal to the phase of the input clock signal.
6. A distributed deskew object of a switch box, wherein the switch box is located at an intersection of a plurality of clock regions, wherein the distributed deskew object comprises:
phase detector circuitry that detects a phase of an input clock signal and a phase of a feedback clock signal;
counter circuitry that has a value that is based at least in part on the phase of the input clock signal and the phase of the feedback clock signal; and
delay circuitry that generates an adjustable delay proportional to the value of the counter circuitry.
7. The distributed deskew object of claim 6 , wherein the phase detector circuitry outputs one or more increments or decrements based at least in part on the phase of the input clock signal and the phase of the feedback clock signal.
8. The distributed deskew object of claim 7 , wherein the phase detector circuitry updates the value of the counter circuitry based at least in part on the one or more increments or decrements.
9. The distributed deskew object of claim 6 , wherein the delay circuitry adjusts the feedback clock signal with the adjustable delay.
10. The distributed deskew object of claim 9 , wherein a phase of the feedback clock signal adjusted with the adjustable delay is substantially equal to the phase of the input clock signal.
11. The distributed deskew object of claim 6 , wherein the delay circuitry comprises a plurality of delay elements.
12. The distributed deskew object of claim 11 , wherein the plurality of delay elements correspond to equally sized delay values.
13. The distributed deskew object of claim 11 , wherein the plurality of delay elements correspond to different delay values.
14. The distributed deskew object of claim 11 , wherein each delay element of the plurality of delay elements comprises a delay block coupled to an input of a multiplexer.
15. The distributed deskew object of claim 14 , wherein the multiplexer selects a delay output corresponding to a respective delay element or a delay output corresponding to a respective previous delay element.
16. A method for providing a deskewed clock signal to a clock region of a plurality of clock regions, the method comprising:
providing a reference clock signal to a switch box connecting the plurality of clock regions;
deskewing a feedback clock signal based on adjusting the feedback clock signal by a delay amount, wherein the delay amount is based on a phase of the feedback clock signal a phase of the reference clock signal;
sending the feedback clock signal adjusted by the delay amount to the clock region of the plurality of clock regions; and
feeding back the feedback clock signal adjusted by the delay amount to the switch box.
17. The method of claim 16 , wherein the reference clock signal is provided by a global clock bus coupled to an intersection of the plurality of clock regions.
18. The method of claim 16 , wherein deskewing the feedback clock signal comprises digitally incrementing or decrementing a control value based at least in part on a difference between the phase of the reference clock signal and the phase of the feedback clock signal.
19. The method of claim 18 , wherein the delay amount is proportional to the control value.
20. The method of claim 16 , wherein a phase of the feedback clock signal adjusted by the delay amount is substantially equal to the phase of the reference clock signal.