Balancing apparatus for signal transmissions

• US 6,031,432 A
• Filed: 02/27/1998
• Issued: 02/29/2000
• Est. Priority Date: 02/28/1997
• Status: Expired due to Term

• Current Assignee: PPC Broadband Incorporated (Belden Inc.)
• Original Assignee: Ronald C. Schreuders
• Inventors: Schreuders, Ronald C.
• Primary Examiner(s): GENSLER, PAUL L
• Application Number:
  US09/032,517
• Time in Patent Office: 732 Days
• Field of Search: 333/4, 333/24, 333/28 R, 333/81 R, 333/167-170, 333/172
• US Class Current: 333/24.00R
• CPC Class Codes: H03H 7/06 including resistors H03H7/075, H03H7/09, H03H7/12, H03H7/13 take precedence
• CPC Class Codes: H03H 7/075 Ladder networks, e.g. electric wave filters
• CPC Class Codes: H03H 7/1758 Series LC in shunt or branch path H03H7/1791 takes precedence

Abstract

This invention discloses a balancing circuit for providing a substantially fixed level of attenuation within a given return path frequency passband, while preventing noise related harmonics from distorting signal transmissions within the return path frequency passband. The balancing circuit includes coupling capacitors which are connected in series between input and output end nodes. A series connected inductor and capacitor pair is connected between each of the input and output end nodes and ground to form end sections. Another inductor is connected between the coupling capacitors and ground. A resistor is connected in parallel with the respective capacitor of each end section. The balancing circuit is placed in series at each subscriber port, and may be mounted on a printed circuit board and enclosed within a tubular housing with mating male and female "F" connections.

Claims

1. A balancing circuit for balancing return path transmissions in a coaxial cable communication system comprising:

a plurality of series coupled capacitors coupled between respective input and output ends;

a first inductor having a first terminal coupled to said input end, and having a second terminal;

a first capacitor having a first terminal coupled to the second terminal of said first inductor, and having a second terminal coupled to ground;

a second inductor having a first terminal coupled to said output end, and having a second terminal;

a second capacitor having a first terminal coupled to the second terminal of said second inductor, and having a second terminal coupled to ground;

a first resistor having a first terminal coupled to the first terminal of said first capacitor, and having a second terminal coupled to ground; and

a second resistor having a first terminal coupled to the first terminal of said second capacitor, and having a second terminal coupled to ground, wherein the balancing circuit substantially equalizes signal attenuation levels within a given return path frequency range.

2. The balancing circuit of claim 1 further comprising a third inductor having a first terminal coupled between a node common to two of the plurality of series coupled capacitors and a second terminal coupled to ground.

3. The balancing circuit of claim 1 comprising at least four said series coupled capacitors, and wherein said first inductor has a first terminal coupled to a node between two of said series coupled capacitors, and wherein said second inductor has a first terminal coupled to a node between the remaining two capacitors of said at least four series coupled capacitors.

4. A balancing circuit for balancing return path transmissions in a coaxial cable communication system, comprising:

a plurality of series coupled capacitors coupled between respective input and output ends;

a first inductor having a first terminal coupled to said input end, and having a second terminal;

a first capacitor having a first terminal coupled to the second terminal of said first inductor, and having a second terminal;

a second inductor having a first terminal coupled to said output end, and having a second terminal;

a second capacitor having a first terminal coupled to the second terminal of said second inductor, and having a second terminal coupled to the second terminal of said first capacitor;

a first resistor having a first terminal coupled to the first terminal of said first capacitor, and having a second terminal coupled to the second terminal of said first capacitor; and

a second resistor having a first terminal coupled to the first terminal of said second capacitor, and having a second terminal coupled to the second terminal of said second capacitor, wherein the balancing circuit substantially equalizes signal attenuation levels within a given return path frequency range.

5. In a coaxial cable communication system, a method of substantially equalizing signal attenuation levels within a given return path frequency range comprising the steps of:

providing an input end, an output end, and a ground;

providing a plurality of series coupled capacitors coupled between said input and output ends;

providing a first capacitor and inductor pair coupled in series between said input end and ground;

providing a second capacitor and inductor pair coupled in series between said output end and ground; and

providing a resistor coupled in parallel with the capacitor of each of said first and second capacitors and inductor pairs so as to reduce a quality factor "Q" of the capacitor of each of said first and second capacitor and inductor pairs such that the balancing circuit provides signals at the output end with substantially fixed levels of attenuation within the given return path frequency range.

6. The method of claim 5, comprising the further step of providing an inductor coupled between a node between said input and output ends and ground such that noise related harmonics are prevented from distorting signals within the given frequency range.

7. A balancing circuit comprising:

an input end;

an output end;

a ground;

means respectively coupled between the input and output ends and ground for substantially equalizing signal attenuation levels within a given return path frequency range; and

means coupled between a node between said input and output ends and ground for filtering signals below said given return path frequency range.

8. A balancing circuit comprising:

a plurality of series coupled capacitors coupled between respective input and output ends;

a first inductor having a first terminal coupled to said input end, and having a second terminal;

a first capacitor having a first terminal coupled to the second terminal of said first inductor, and having a second terminal coupled to ground;

a second inductor having a first terminal coupled to said output end, and having a second terminal;

a second capacitor having a first terminal coupled to the second terminal of said second inductor, and having a second terminal coupled to ground;

a first resistor having a first terminal coupled to the first terminal of said first capacitor, and having a second terminal coupled to ground;

a second resistor having a first terminal coupled to the first terminal of said second conductor, and having a second terminal coupled to ground; and

a third inductor having a first terminal coupled between a node common to two of the plurality of series coupled capacitors and a second terminal coupled to ground.

9. A balancing circuit comprising:

a plurality of series coupled capacitors coupled between respective input and output ends;

a first inductor having a first terminal coupled to said input end, and having a second terminal;

a first capacitor having a first terminal coupled to the second terminal of said first inductor, and having a second terminal coupled to ground;

a second inductor having a first terminal coupled to said output end, and having a second terminal;

a second capacitor having a first terminal coupled to the second terminal of said second inductor, and having a second terminal coupled to ground;

a first resistor having a first terminal coupled to the first terminal of said first capacitor, and having a second terminal coupled to ground;

a second resistor having a first terminal coupled to the first terminal of said second capacitor, and having a second terminal coupled to ground;

wherein there are at least four said series coupled capacitors, and wherein said first inductor has a first terminal coupled to a node between two of said series coupled capacitors, and wherein said second inductor has a first terminal coupled to a node between the remaining two capacitors of said at least four series coupled capacitors.

10. A method of substantially equalizing signal attenuation levels within a given frequency range comprising the steps of:

providing an input end, an output end, and a ground;

providing a plurality of series coupled capacitors coupled between said input and output ends;

providing a first capacitor and inductor pair coupled in series between said input end and ground;

providing a second capacitor and inductor pair coupled in series between said output end and ground;

providing a resistor coupled in parallel with the capacitor of each of said first and second capacitors and inductor pairs so as to reduce a quality factor "Q" of the capacitor of each of said first and second capacitor and inductor pairs; and

providing an inductor coupled between a node between said input and output ends and ground such that noise related harmonics are prevented from distorting signals within the given frequency range.

11. A balancing circuit for balancing return path transmissions in a coaxial cable communication system comprising:

a plurality of series coupled capacitors coupled between respective input and output ends;

a first inductor having a first terminal coupled to said input end, and having a second terminal;

a first capacitor having a first terminal coupled to the second terminal of said first inductor, and having a second terminal coupled to ground;

a second inductor having a first terminal coupled to said output end, and having a second terminal;

a second capacitor having a first terminal coupled to the second terminal of said second inductor, and having a second terminal coupled to ground;

a first resistor having a first terminal coupled to the first terminal of said first inductor, and having a second terminal coupled to the second terminal of said first inductor; and

a second resistor having a first terminal coupled to the first terminal of said second inductor, and having a second terminal coupled to the second terminal of said second inductor, wherein the balancing circuit substantially equalizes signal attenuation levels within a given return path frequency range.

12. The balancing circuit of claim 11 further comprising a third inductor having a first terminal coupled between a node common to two of the plurality of series coupled capacitors and a second terminal coupled to ground.