Dual-mode clock for improved power management in a wireless device

• US 7,321,755 B2
• Filed: 07/30/2003
• Issued: 01/22/2008
• Est. Priority Date: 07/31/2002
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Hulvey, Robert W.
• Primary Examiner(s): Jackson; Blane J.
• Application Number:
  US10/630,285
• Publication Number:
  US 20040023680A1
• Time in Patent Office: 1,637 Days
• Field of Search: 455/258, 455/256, 455/259, 455/318, 455/343.1, 455/343.2, 455/343.3, 455/574, 370/311
• US Class Current: 455/343.1
• CPC Class Codes: G06F 1/3215 Monitoring of peripheral devices
• CPC Class Codes: G06F 1/324 by lowering clock frequency
• CPC Class Codes: G06F 1/325 Power saving in peripheral device
• CPC Class Codes: G06F 1/3259 Power saving in cursor control device, e.g. mouse, joystick, trackball
• CPC Class Codes: G06F 1/3271 Power saving in keyboard
• CPC Class Codes: G06F 3/0231 Cordless keyboards
• CPC Class Codes: H04M 1/72412 using two-way short-range wireless interfaces
• CPC Class Codes: H04W 52/029 reducing the clock frequency of the controller
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A dual mode clock for providing first and second clock signals to a wireless interface unit. The first and second clock signals correspond to first and second operating states of the wireless interface unit. In the first operating state, the transceiver in the RF analog module is operational and the clock generator provides a first clock signal having low phase-noise characteristics necessary to maintain efficient operation of the transceiver. In a second operating state, the transceiver in the RF analog module is turned off. In this second operational state, the clock generator provides a second clock signal having a quality sufficient to maintain efficient operation of the digital baseband module in the wireless interface. By switching between low-power mode and normal mode, the system is operable to provide a high quality clock signal for use by the RF analog module when it is operational and to provide a lower power, lower quality clock signal which is sufficient for use by the baseband digital unit when the transceiver in the RF analog module is powered down.

Claims

1. A system for managing power in a wireless interface system that services communications between a wirelessly enabled host and at least one user input device, comprising:

a wireless interface unit that wirelessly interfaces with the wirelessly enabled host, wherein the wireless interface unit comprises;

an analog module including a transceiver unit, a baseband core digital module further comprising;

a transceiver operation detector operable to detect operation of the transceiver unit, and

a voltage regulator control signal generator operable to generate a voltage regulator reference control signal corresponding to the operational status of the transceiver;

a clock generator operable to generate first and second clock signals corresponding to a first operating state wherein the transceiver is operational and a second operating state wherein the transceiver is turned off;

a processing unit operably coupled to the wireless interface unit, said processing unit operable to use said reference control signal to generate a low power mode signal; and

a power management unit operably coupled to the wireless interface unit, the processing unit, and the clock generator, wherein the power management unit is operable to receive said low power mode signal and to control the power consumption of the wireless interface unit by providing a first power level to the clock generator when low power mode signal is in a first state and providing a second power level to the clock generator when the low power mode signal is in a second state.

2. The wireless interface device of claim 1, wherein the wireless interface device enters one of a plurality of power consumption operating states comprising:

busy mode in which all components of the wireless interface device are powered and operational;

idle mode in which the wireless interface unit performs first power conserving operations;

suspend mode in which the wireless interface unit performs second power conserving operations; and

power down mode in which the wireless interface unit and the processing unit are powered down.

3. The wireless interface device of claim 2, wherein in the idle mode the wireless interface unit periodically communicates with the wirelessly enabled host.

4. The wireless interface device of claim 2 wherein in the suspend mode:

the wireless interface unit does not transmit to the wirelessly enabled host; and

the wireless interface unit listens to the transmissions of the wirelessly enabled host.

5. The wireless interface device of claim 4, wherein the power management unit powers down the wireless interface unit and the processing unit after at least one inactivity period during which the at least one user input device is inactive with respect to the input/output unit.

6. The wireless interface device of claim 1, wherein the user input device includes a cursor control device.

7. The wireless interface device of claim 1, wherein the user input device includes a keypad.

8. The wireless interface device of claim 1, wherein the user input device includes:

a cursor control device; and

a keypad.