Stability robustness using a non-integer order filter in a circuit
View Patent ↗A non-integer order controller for providing stability in a circuit. The non-integer order controller may be in either a feed-forward path or a feedback path of the circuit. Thus, the non-integer order controller is operable to provide stability for the circuit. The closed loop system may be a phase lock loop.
1. A device for providing stability in a circuit comprising:
a non-integer order controller in one of a feed-forward path and a feedback path of said circuit, wherein said non-integer order controller is operable to provide stability for said circuit.
2. The device of claim 1 , wherein said non-integer order controller is in said feed-forward path.
3. The device of claim 1 , wherein said non-integer order controller is in said feedback path.
4. The device of claim 1 , wherein said circuit is a phase lock loop.
5. The device of claim 4 , wherein poles and zeroes of said non-integer order controller each have a respective pre-determined value to minimize a settling time of said phase lock loop.
6. The device of claim 1 , wherein said non-integer order controller comprises circuit elements configured in a recursive pattern.
7. The device of claim 1 , wherein said non-integer order controller is implemented with computer software.
8. A method of providing stability to a system, comprising:
a) receiving a signal in a closed loop system;
b) modifying said signal with a non-integer order function to provide stability to said system; and
c) passing said signal along in said closed loop system.
9. The method of claim 8 , wherein said system comprises a phase lock loop.
10. The method of claim 8 , wherein said b) comprises modifying said signal using software.
11. The method of claim 8 , wherein said b) comprises modifying said signal using hardware.
12. The method of claim 8 , wherein said a) comprises receiving said signal from a feed-forward path of said closed loop system.
13. The method of claim 8 , wherein said a) comprises receiving said signal from a feedback path of said closed loop system.
14. A phase lock loop circuit comprising:
a feed-forward path;
a feedback path coupled to said feed-forward path; and
a non-integer order controller in one of said feed-forward path and said feedback path and operable to provide stability.
15. The phase lock loop circuit of claim 14 , wherein said non-integer order controller comprises circuit elements in a recursive pattern.
16. The phase lock loop circuit of claim 15 , wherein said circuit elements comprise resistors and capacitors.
17. The phase lock loop circuit of claim 14 , wherein said non-integer order controller is further operable as a low pass filter.
18. The phase lock loop circuit of claim 14 , wherein poles and zeroes of said non-integer order controller have pre-determined values to minimize a settling time of said phase lock loop.
19. The phase lock loop circuit of claim 14 , wherein said non-integer order controller comprises poles and zeroes that are operable to simulate a single pole/single zero filter of order m, wherein m is a non-integer and wherein m is a pre-determined value operable to improve a figure of merit of said phase lock loop.
20. The phase lock loop circuit of claim 19 , wherein said value of m is operable to reduce a locking time of said phase lock loop as compared to an integer order controller.