Mobile device and method for the management of a standby mode in a mobile device of this kind

• US 6,650,189 B1
• Filed: 03/31/2000
• Issued: 11/18/2003
• Est. Priority Date: 04/01/1999
• Status: Expired due to Fees

• Current Assignee: Sagem SA (Safran SA)
• Original Assignee: Sagem SA (Safran SA)
• Inventors: Romao, Fernando
• Primary Examiner(s): KINKEAD, ARNOLD M
• Application Number:
  US09/541,412
• Time in Patent Office: 1,327 Days
• Field of Search: 455/89, 455/343, 455/574, 331/49, 331/74, 331/46, 327/144, 713/322, 713/323, 713/500
• US Class Current: 331/49
• CPC Class Codes: H04B 1/1615 Switching on; Switching off, e.g. remotely battery saving circuits associated with selective call operation H04W52/00; details of power consumption reduction in a PLL, H03L7/0802, H03L7/14, H03L2207/08, H03L2207/18; muting amplifiers by gain control see H03G3/34
• CPC Class Codes: H04W 52/0287 changing the clock frequency of a controller in the equipment
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

An RC type oscillator (10) is integrated into a processor circuit (2) of a mobile device (1). This oscillator is used to set the pace of the activity of the processor circuit during periods when the mobile device is on standby. The frequency drift due to the temperature variations of the oscillator is concerted by a regular calibration of the oscillator by a faster oscillator recognized to be stable. This embodiment gives gain in space and a reduction in cost.

Claims

1. A mobile device comprising:

a processor integrated circuit needed to implement activity of the mobile device,

means to place this device in standby mode and active mode,

two oscillators to set the pace of the processor integrated circuit, a first slow oscillator useful in a standby mode, and a second fast oscillator useful in an active mode, wherein;

the slow oscillator is an RC type oscillator and is contained in the processor integrated circuit; and

the device further comprises a memory register to store a measurement of frequency drift of the slow oscillator.

2. A device according to claim 1, wherein the slow oscillator has an inverter whose input is connected to a potential by a capacitor and whose output is connected to the input by a resistor.

3. A mobile device comprising:

a processor integrated circuit needed to implement the activity of the mobile device,

means to place this device in standby mode and active mode,

two oscillators to set the pace of the processor integrated circuit, a first slow oscillator useful in a standby mode, and a second fast oscillator useful in an active mode, wherein;

the slow oscillator is an RC type oscillator and is contained in the processor integrated circuit; and

the slow oscillator comprises a voltage-controlled oscillator whose output is connected to a lowpass filter cascade-connected with a first input of a voltage comparator, a second input of the comparator being connected to a reference voltage generator, the output of the comparator being connected to the control input of the voltage-controlled oscillator.

4. A method for the management of a standby mode of a mobile device wherein:

the device is made to work in active mode by means of a fast oscillator recognized to be stable,

for a standby mode of the device, there is provided a date of activation of the device, this date being stored in a register,

parameters useful for the management of the standby mode are computed, and the parameters are stored in a memory,

the device is placed in standby mode and then the device is repositioned in active mode on the planned date of activation by means of a slow oscillator,

wherein just before a passage into standby mode and regularly during this standby mode;

a slow RC oscillator is calibrated with the fast oscillator,

the result of the calibration is stored in a register,

a duration of inter-calibration is planned,

the slow RC oscillator is calibrated again at the end of the inter-calibration period.

5. Method according to claim 4, wherein

the inter-calibration duration is provided for by means of a counter, and

whenever the counter reaches a threshold:

the fast oscillator is put into operation,

the slow RC oscillator is calibrated with the fast oscillator,

the result of the calibration is compared with that of a previous calibration and the duration of inter-calibration is adjusted as a function of the difference between these results, the greater the difference, the smaller being the duration of inter-calibration.

6. A mobile device having a standby mode and an active mode, the mobile device comprising:

a bus;

a microprocessor coupled to the bus;

a selector coupled to the bus;

a fast quartz oscillator coupled to the selector, the fast quartz oscillator setting the pace of the mobile device in the active mode; and

an RC type slow oscillator coupled to the selector, the RC type slow oscillator setting the pace of the mobile device in the standby mode,

wherein when the device enters the standby mode, the microprocessor actuates the selector to enable the RC type slow oscillator and when the device enters the active mode, the microprocessor actuates the selector to enable the fast quartz oscillator, the device further comprising a register,

wherein a calibration value is stored in the register, the calibration value corresponding to a result of a calibration between the RC type slow oscillator and the fast quartz oscillator during the standby mode.