Apparatus for and method of reducing power consumption in a cable modem

• US 7,523,329 B2
• Filed: 06/19/2007
• Issued: 04/21/2009
• Est. Priority Date: 07/19/2006
• Status: Active Grant

• Current Assignee: Maxlinear Incorporated
• Original Assignee: Texas Instruments, Inc.
• Inventors: Ezra, Ronen, Klein, Shaul
• Primary Examiner(s): Lee; Thomas
• Assistant Examiner(s): Bae; Ji H
• Application Number:
  US11/764,914
• Publication Number:
  US 20080018427A1
• Time in Patent Office: 672 Days
• Field of Search: 713/300, 713/320, 713/324, 713/340
• US Class Current: 713/320
• CPC Class Codes: H04L 1/22 using redundant apparatus to increase reliability

Abstract

A novel apparatus and method of reduced power consumption for battery backup operation of a communication device such as a cable modem. When the cable modem senses a failure of the external power source it requests from the cable head-end to switch from multi-channel DOCSIS 3.0 operation to single-channel DOCSIS 2.0 operation. In response to approval by the cable head-end, the cable modem shuts down multi-channel circuits in the PHY such as the wideband analog to digital converter (ADC) which is normally used during multi-channel operation. In its place, it activates narrowband circuitry such as a narrowband ADC which consumes far less power. Tuner filter circuits are also swapped to match the reduced bandwidth requirements of battery backup operation. To further reduce power, the narrower bandwidth requirements during battery backup operation permit the linearity of a programmable gain amplifier (PGA) in the upstream path to be reduced.

Claims

1. A method of reducing power consumption in a cable modem coupled to a cable head-end and incorporating a PHY circuit having a normally active multi-channel wideband mode and single-channel narrowband mode of operation, said method comprising the steps of:

sensing loss of external power to said cable modem;

requesting from said cable head-end to switch to said single-channel narrowband mode of operation; and

upon approval from said cable head-end, shutting down said multi-channel wideband mode of operation and activating said single-channel narrowband mode of operation by configuring a tuner circuit to switch to a narrow band intermediate frequency (IF) channel utilizing a surface acoustic wave (SAW) filter circuit.

2. The method according to claim 1, wherein said step of activating said single-channel narrowband mode of operation comprises the steps of:

shutting down a wideband analog to digital converter (ADC) circuit; and

activating a narrowband ADC circuit.

3. The method according to claim 1, wherein said single-channel narrowband mode of operation comprises Data Over Cable Service Interface Specification (DOCSIS) 2.0 single-channel operation.

4. The method according to claim 1, wherein said multi-channel wideband mode of operation comprises Data Over Cable Service Interface Specification (DOCSIS) 3.0 multiple channel operation.

5. The method according to claim 1, wherein said step of requesting comprises sending a Data Over Cable Service Interface Specification (DOCSIS) 3.0 CM-STATUS message to a cable modem termination system (CMTS) indicating a loss of external power.

6. The method according to claim 1, wherein said step of activating comprises the step of lowering a sampling clock rate of an analog to digital converter (ADC).

7. An apparatus for reducing power consumption in a cable modem coupled to a cable modem termination service (CMTS), comprising:

a power supply control circuit coupled to an external power source and a battery, said power supply control circuit operative to sense a failure of said external power source and switch to battery backup;

an analog front end (AFE) circuit comprising a wideband analog to digital converter (ADC) and a narrowband ADC; and

a wideband/narrowband (WB/NB) control circuit operative to receive an indication of a loss of external power from said power supply circuit and to shut down said wideband ADC and activate said narrowband ADC in response thereto, wherein said WB/NB control circuit further comprises means for configuring a tuner circuit coupled to said AFE to switch to a narrow band intermediate frequency (IF) channel utilizing a surface acoustic wave (SAW) filter circuit in the event of a loss of external power.

8. The apparatus according to claim 7, wherein said WB/NB control circuit is operative to shut down said wideband ADC and activate said narrowband ADC upon approval from said CMTS.

9. The apparatus according to claim 7, wherein said narrowband ADC is used during Data Over Cable Service Interface Specification (DOCSIS) 2.0 single-channel operation.

10. The apparatus according to claim 7, wherein said wideband ADC is used during Data Over Cable Service Interface Specification (DOCSIS) 3.0 multiple channel operation.

11. The apparatus according to claim 7, wherein said WB/NB control circuit is operative to lower a sampling clock rate of an analog to digital converter (ADC) circuit within said AFE in the event of a loss of external power.

12. A method of reducing power consumption in a cable modem coupled to a cable head-end and incorporating a PHY circuit having a normally active multi-channel wideband mode and single-channel narrowband mode of operation, said method comprising the steps of:

switching from said multi-channel wideband mode of operation to said single-channel narrowband mode of operation in response to sensing a loss of external power to said cable modem;

configuring a tuner circuit to switch to a narrow band intermediate frequency (IF) channel utilizing a surface acoustic wave (SAW) filter circuit; and

switching from said single-channel narrowband mode of operation back to said multi-channel wideband mode of operation in response to sensing the restoration of external power to said cable modem.

13. The method according to claim 12, comprising the steps of:

shutting down a wideband analog to digital converter (ADC) circuit; and

activating a narrowband ADC circuit.

14. The method according to claim 12, wherein said step of switching from said single-channel narrowband mode of operation back to said multi-channel wideband mode of operation comprises the steps of:

configuring the tuner circuit to switch to a wideband intermediate frequency (IF) channel;

shutting down a narrowband analog to digital converter (ADC) circuit; and

activating a wideband ADC circuit.

15. The method according to claim 12, wherein said single-channel narrowband mode of operation comprises Data Over Cable Service Interface Specification (DOCSIS) 2.0 single-channel operation.

16. The method according to claim 12, wherein said multi-channel wideband mode of operation comprises Data Over Cable Service Interface Specification (DOCSIS) 3.0 multiple channel operation.

17. The method according to claim 12, wherein said step of requesting comprises sending a Data Over Cable Service Interface Specification (DOCSIS) 3.0 CM-STATUS message to a cable modem termination system (CMTS) indicating a loss of external power.

18. The method according to claim 13, wherein said step of activating comprises the step of lowering a sampling clock rate of an analog to digital converter (ADC).

19. A method of reducing power consumption in a communications device incorporating a PHY circuit having a normally active multi-channel wideband mode and single-channel narrowband mode of operation, said method comprising the steps of:

sensing loss of external power to said communications device;

requesting to switch to said single-channel narrowband mode of operation; and

upon approval, shutting down said multi-channel wideband mode of operation and activating said single-channel narrowband mode of operation; and

configuring a tuner circuit to switch to a narrow band intermediate frequency (IF) channel utilizing a surface acoustic wave (SAW) filter circuit.

20. The method according to claim 19, further comprising the steps of:

sensing the restoration of external power to said communications device;

requesting to switch to said multi-channel wideband mode of operation; and

upon approval, shutting down said single-channel narrowband mode of operation and activating said multi-channel wideband mode of operation.

21. A cable modem coupled to a cable head-end over a cable network, comprising:

a memory;

one or more interface ports;

a tuner coupled to a CATV cable having a plurality of channels, said tuner operative to tune a received broadband signal in accordance with a tune command;

a PHY circuit coupled to said tuner comprising a wideband analog to digital converter (ADC) and a narrowband ADC, said PHY circuit operative to generate a baseband signal from the output of said tuner;

a programmable gain amplifier (PGA) in an upstream path;

means for reducing power consumption of said cable modem in the event of a loss of external power operative to decrease the current consumption of said PGA thereby reducing its linearity resulting in a reduction in power consumption of said cable modem, said means for reducing power consumption comprising;

means for sensing loss of external power to said cable modem;

means for requesting from said cable head-end to switch to said single-channel narrowband mode of operation;

upon approval from said cable head-end, shutting down said multi-channel wideband mode of operation and activating said single-channel narrowband mode of operation.

22. The cable modem according to claim 21, wherein said means for reducing power consumption further comprises:

means for sensing the restoration of external power to said cable modem;

means for requesting to switch to said multi-channel wideband mode of operation; and

means for upon approval, shutting down said single-channel narrowband mode of operation and activating said multi-channel wideband mode of operation.

23. The cable modem according to claim 21, wherein said tuner comprises a wideband intermediate frequency (IF) channel and a narrowband IF channel wherein said step of activating comprises configuring said tuner to use said narrowband IF channel.