Ultra-high-frequency notch filter

• US 20050059998A1
• Filed: 09/12/2003
• Published: 03/17/2005
• Est. Priority Date: 09/12/2003
• Status: Active Grant

• Current Assignee: Avaya Incorporated
• Original Assignee: Avaya Incorporated
• Inventors: Norte, David A., Yoon, Woong K.
• Granted Patent: US 7,427,904 B2
• Time in Patent Office: Days
• US Class Current: 607/2
• CPC Class Codes: H05K 1/0233 Filters, inductors or a magnetic substance
• CPC Class Codes: H05K 2201/1006 Non-printed filter
• CPC Class Codes: H05K 2201/10636 Leadless chip, e.g. chip capacitor or resistor
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

An ultra-high-frequency notch filter (100) comprises a capacitor (102) defining a conductive trace (106) on its body (103) and extending between its terminals (104). The trace has an inductance that forms a parallel LC circuit with the capacitance of the capacitor. When mounted on a printed circuit board (120) to connect two segments of a signal line (124), the notch filter and a ground plane (122) of the PCB form a virtual conductive loop having an inductance and a capacitance whose product is the center frequency of the notch of the notch filter. The center ferquency is tuned by varying the width of the trace.

Claims

1. An apparatus comprising:

a capacitor having a body and a pair of terminals attached to the body; and

a conductor defined on the body and connecting the terminals, the conductor having an inductance (L) defining with a capacitance (C) of the capacitor a parallel LC circuit.

2. The apparatus of claim 1 wherein:

the conductor is plated on the body.

3. The apparatus of claim 1 wherein:

the conductor is printed on the body.

4. The apparatus of claim 1 wherein:

the conductor has a width defining the inductance such that the inductance is varied by varying the width of the conductor.

5. The apparatus of claim 1 forming a notch filter.

6. The apparatus of claim 5 wherein:

the capacitor has a resonant frequency greater than or equal to a notch center frequency of the notch filter.

7. A notch filter having a notch center frequency, comprising:

a capacitor having a body and a pair of terminals attached to the body, the capacitor having a resonant frequency equal to or greater than the notch center frequency; and

a conductive trace extending along the body and connecting the terminals, the trace having an inductance.

8. The notch filter of claim 7 wherein:

the trace is defined on the body.

9. The notch filter of claim 8 wherein:

the trace is plated on the body.

10. The notch filter of claim 8 wherein:

the trace is printed on the body.

11. The notch filter of claim 7 wherein:

the trace has a width defining the inductance such that the inductance is varied by varying the width of the trace.

12. The notch filter of claim 7 for connecting between two discrete segments of a signal conductor defined by a printed circuit board that also defines a ground plane, wherein:

a product of capacitance and inductance of a virtual conductive loop formed by the notch filter and the ground plane equals the notch center frequency.

13. A printed circuit board (PCB) comprising:

a signal conductor comprising a pair of discrete conductor segments defined by the PCB;

a ground plane defined by the PCB;

a capacitor having a body and a pair of terminals on the body that connect the capacitor between the segments;

a conductor defined on the body and connecting the pair of terminals and having an inductance, the conductor forming with the capacitor a notch filter for the signal conductor such that a product of capacitance and inductance of a virtual conductive loop formed by the notch filter and the ground plane equals a center frequency of a notch of the notch filter.

14. The PCB of claim 13 wherein:

the capacitor has a resonant frequency equal to or greater than the center frequency of the notch filter.

15. The PCB of claim 13 wherein:

the conductor is plated on the body.

16. The PCB of claim 13 wherein:

the conductor is printed on the body.

17. The PCB of claim 13 wherein:

the capacitor is a surface-mount capacitor.

18. The PCB of claim 13 wherein:

the conductor has a width defining the inductance of the conductor such that the notch filter is tuned by varying the width of the conductor.