Signal coupler using high voltage and low voltage filtering

• US 20020136394A1
• Filed: 02/15/2002
• Published: 09/26/2002
• Est. Priority Date: 04/09/1998
• Status: Abandoned Application

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Inventors: Rosen, Mark, Snow, Dane Roderick
• Application Number:
  US10/077,570
• Publication Number:
  US 20020136394A1
• Time in Patent Office: Days
• US Class Current: 379/399.01
• CPC Class Codes: H04L 27/0002 analog front ends; means for connecting modulators, demodulators or transceivers to a transmission line duplex arrangements H04L5/143
• CPC Class Codes: H04M 3/005 Interface circuits for subscriber lines current supply H04M19/00 and subgroups; supervisory, monitoring or testing arrangements H04M3/22 and subgroups; in key telephone systems H04M9/006
• CPC Class Codes: H04M 3/007 Access interface units for simultaneous transmission of speech and data, e.g. digital subscriber line [DSL] access interface units DSL access multiplexers H04Q11/0478, and H04L12/2856

Abstract

A signal coupler is provided which decreases the number of discreet elements required to provide low pass filtering for the plain old telephone service (POTS). The low pass filtering is shifted to areas of the signal coupler circuit which do not operate with the high battery voltage present on telephone lines. The low voltage filtering reduces the need for components, which are capable of operating in the high voltage environment and therefore reduces the space on the circuit board, which is occupied by each of the signal couplers. In this way, the number of individual subscriber lines that a given circuit board can accommodate can be increased.

Claims

1. A signal coupler comprises:

high-voltage low pass filter operably coupled to low pass filter an analog signal to produce a partially filtered Plain Old Telephone System (POTS) signal;

subscriber loop interface circuit operably coupled to provide a two-wire to four-wire interface conversion between a PTIP line and PRING line carrying the filtered POTS signal, a transmit line pair, and a receive line pair,

wherein an incoming portion of the partially filtered POTS signal is provided on the transmit line pair; and

low-voltage low pass filter operably coupled to low pass filter the incoming portion of the partially filtered POTS signal to produce a filtered incoming POTS signal.

2. The signal coupler of claim 1, wherein the high-voltage low pass filter further comprises:

a pair of resistors;

a pair of inductors; and

a capacitor operably coupled to the pair of resistors and to the pair of inductors to provide a single stage-second order low pass filter.

3. The signal coupler of claim 2, wherein the low-voltage low pass filter further comprises:

continuous time low pass filter stage operably coupled to provide second order filtering of the incoming portion of the partially filtered POTS signal to produce the filtered incoming POTS signal.

4. The signal coupler of claim 2, wherein the low-voltage low pass filter further comprises:

first continuous time low pass filter stage operably coupled to provide second order filtering of the incoming portion of the partially filtered POTS signal to produce a first filtered incoming POTS signal;

second continuous time low pass filter stage operably coupled to provide second order filtering of the first filtered incoming POTS signal to produce a second filtered incoming POTS signal; and

third continuous time low pass filter stage operably coupled to provide second order filtering of the second filtered incoming POTS signal to produce the filtered incoming POTS signal.

5. The signal coupler of claim 1 further comprises:

coding/decoding circuit operably coupled to the filtered incoming POTS signal into a digital POTS signal; and

digital low pass filter operably coupled to digitally low pass filter the digital POTS signal to produce a filtered POTS signal.

6. The signal coupler of claim 1 further comprises:

high pass filter operably coupled to high pass filter the analog signal to produce data signals; and

hybrid operably coupled to provide a two-wire to four-wire interface between a line carrying the data signals and a transmit line and a receive line.