Filter shaping using a signal cancellation function

• US 8,380,771 B2
• Filed: 03/27/2009
• Issued: 02/19/2013
• Est. Priority Date: 03/27/2009
• Status: Active Grant

• Current Assignee: Intersil Americas LLC (Renesas Electronics Corporation)
• Original Assignee: Quellan, Inc. (Renesas Electronics Corporation)
• Inventors: Hahn, Wilhelm Steffen, Chen, Wei
• Primary Examiner(s): Mai, Tan V.
• Application Number:
  US12/413,454
• Publication Number:
  US 20100244943A1
• Time in Patent Office: 1,425 Days
• Field of Search: 708300-323
• US Class Current: 708/309
• CPC Class Codes: G06F 17/00 Digital computing or data processing equipment or methods, specially adapted for specific functions information retrieval, database structures or file system structures therefor G06F16/00
• CPC Class Codes: H03H 11/1291 Current or voltage controlled filters
• CPC Class Codes: H03H 2011/0488 Notch or bandstop filters
• CPC Class Codes: H03K 5/125 Discriminating pulses measuring characteristics of individual pulses G01R29/02; separation of synchronising signals in television systems H04N5/08

Abstract

A signal filter and accompanying methods. In one embodiment, the filter includes a first mechanism for receiving a first signal. A second mechanism employs one or more modified representations of the first signal to cancel one or more frequency components of the first signal, yielding an output signal in response thereto. In a more specific embodiment, the first mechanism includes a splitter for receiving the first signal and splitting the first signal onto a first path and a second path. The second mechanism further includes one or more delay modules and one or more phase shifters in the first path and/or the second path. One or more controllable amplifiers are optionally included in the first path and/or the second path. The one or more delay modules, phase shifters, or amplifiers are responsive to one or more control signals from a controller. The controller is adapted to modify behavior of the second mechanism so that the filter is characterized by a desired frequency response.

Claims

1. A filter comprising:

first means for receiving a first signal; and

second means for employing one or more modified representations of the first signal to suppress one or more frequency components of the first signal, yielding an output signal in response thereto,

wherein the first means includes a splitter adapted to receive the first signal and split the first signal onto a first path and a second path, and

wherein the second means includes one or more delay modules and one or more phase shifters in the first path and/or the second path.

2. The filter of claim 1, further including one or more amplifiers in the first path or the second path.

3. The filter of claim 2, wherein one or more of the one or more delay modules, phase shifters, or amplifiers are responsive to one or more control signals from a controller.

4. The filter of claim 3, wherein the controller is adapted to modify behavior of the second means so that the filter is characterized by a desired frequency response.

5. A filter comprising:

first means for receiving a first signal; and

second means for employing one or more modified representations of the first signal to suppress one or more frequency components of the first signal, yielding an output signal in response thereto,

wherein the filter implements a controllable notch filter, the controllable notch filter being controllable in part via one or more controllable Variable Gain Amplifiers (VGAs) included in the second means, the one or more controllable VGAs affecting alignment of a modified representation of the first signal relative to the first signal itself.

6. The filter of claim 5, wherein the second means includes third means for combining the modified representation of the first signal with the first signal to yield an output signal, wherein the output signal is representative of the first signal with certain frequency components thereof cancelled or suppressed.

7. The filter of claim 5, wherein one or more instances of the notch filter are implemented in a combined filter that includes a second filter.

8. The filter of claim 7, wherein a transfer function or frequency response of the combined filter is characterized by an asymmetrical frequency response curve.

9. The filter of claim 7, wherein the second filter includes a bandpass filter.

10. The filter of claim 9, further including a controller in communication with the one or more instances of the notch filter.

11. The filter of claim 10, wherein the controller includes instructions for calibrating the combined filter to yield a combined desired transfer function based on one or more predetermined inputs to the controller.

12. The filter of claim 11, wherein the one or more predetermined inputs include temperature.

13. A filter comprising:

a first circuit that is operative to receive a first signal and that comprises a splitter, the splitter operative to split the first signal onto a first path and a second path; and

a second circuit employing one or more modified representations of the first signal to suppress one or more frequency components of the first signal, yielding an output signal in response thereto, wherein the second circuit comprises at least one delay module and at least one phase shifter in the first path and/or the second path.

14. The filter of claim 13, wherein the first path comprises an amplifier.

15. The filter of claim 13, wherein the first path comprises an amplifier that is responsive to a control signal from a controller.

16. The filter of claim 13, wherein the second path comprises an amplifier.

17. The filter of claim 13, wherein the second path comprises an amplifier that is responsive to a control signal from a controller.

18. The filter of claim 13, wherein the first path comprises a first amplifier and the second path comprises a second amplifier.

19. The filter of claim 13, wherein the at least one phase shifter is responsive to a control signal from a controller.

20. The filter of claim 13, wherein the at least one delay module is responsive to a control signal from a controller.

21. The filter of claim 13, wherein the filter is connected to a controller that is operative to modify behavior of the second circuit so that the filter is characterized by a desired frequency response.

22. The filter of claim 13, wherein the filter implements a controllable notch filter.

23. The filter of claim 13, wherein the filter comprises a controllable notch filter that is controllable via one or more controllable Variable Gain Amplifiers (VGAs).

24. The filter of claim 13, wherein the filter is controllable by a Variable Gain Amplifier (VGA) that affects alignment of a modified representation of the first signal relative to the first signal.

25. A filter comprising:

a first circuit that is operative to receive a first signal; and

a second circuit that employs at least one modified representation of the first signal to suppress at least one frequency component of the first signal, yielding an output signal in response thereto,

wherein the filter implements a controllable notch filter, the controllable notch filter being controllable at least in part by at least one controllable variable gain amplifier that is included in the second circuit and that affects alignment of a modified representation of the first signal relative to the first signal itself.

26. The filter of claim 25, wherein the second circuit is operative to combine the modified representation of the first signal with the first signal to yield an output signal, wherein the output signal is representative of the first signal with a frequency component thereof cancelled or suppressed.

27. The filter of claim 25, wherein one or more instances of the notch filter are implemented in a combined filter that includes a second filter.

28. The filter of claim 25, wherein the notch filter comprises a combined filter.

29. The filter of claim 25, wherein the notch filter comprises a combined filter having a transfer function or frequency response that is characterized by an asymmetrical frequency response curve.

30. The filter of claim 25, wherein the notch filter has a transfer function or frequency response characterized by an asymmetrical frequency response curve.

31. The filter of claim 25, wherein the notch filter is implemented in a combined filter that comprises a bandpass filter.

32. The filter of claim 25, wherein the filter is connected to a controller that is operative to modify behavior of the second circuit so that the filter is characterized by a desired frequency response.

33. The filter of claim 25, further including a controller in communication with the one or more instances of the notch filter.

34. The filter of claim 25, further including a controller that comprises calibration instructions.

35. The filter of claim 25, further including a controller that has temperature as an input.