Methods and systems for frequency generation for wireless devices
AssigneeEricsson Inc.
InventorsJohn W. Northcutt, Paul Wilkinson Dent, Eric Alan Shull, Harvey Zien
Life of this patent
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Abstract
Methods and systems are provided for frequency generation suitable for use in wireless devices capable of operating at multiple frequencies. Such systems may change the loop gain of an automatic frequency control loop based on the operating frequency of the wireless device. Furthermore, such a frequency dependent loop gain may be carried out by the selection of subroutines with differing loop gains associated with the subroutines. Furthermore, the loop gain may also be temperature compensated based on the temperature of the wireless device and/or the operating frequency of the device.
Claims44
A method of synchronizing a voltage controlled oscillator which provides a local reference frequency in a wireless device to a received reference frequency, wherein the wireless device operates in at least two frequency bands, the method comprising the steps of:
- determining the frequency band of operation of the wireless device;
- adjusting a loop gain value based on the determined frequency band of operation of the wireless device;
- providing a control voltage to the voltage controlled oscillator based on the determined frequency band of operation of the wireless device so as to provide a frequency adjusted local reference frequency;
- revising the control voltage provided to the voltage controlled oscillator based on an error associated with the frequency adjusted local reference frequency, based on the received reference frequency and based on the adjusted loop gain;
- and
- compensating the loop gain based on an operating temperature of the wireless device.
A method of synchronizing a voltage controlled oscillator which provides a local reference frequency in a wireless device to a received reference frequency, wherein the wireless device operates in at least two frequency bands, the method comprising the steps of:
- determining the frequency band of operation of the wireless device;
- adjusting a loop gain value based on the determined frequency band of operation of the wireless device;
- providing a control voltage to the voltage controlled oscillator based on the determined frequency band of operation of the wireless device so as to provide a frequency adjusted local reference frequency;
- revising the control voltage provided to the voltage controlled oscillator based on an error associated with the frequency adjusted local reference frequency, based on the received reference frequency and based on the adjusted loop gain;
- detecting a change in sign of the error associated with the frequency adjusted local reference frequency;
- and
- decreasing the loop gain value if a change in the sign of the error is detected.
A method of synchronizing a voltage controlled oscillator which provides a local reference frequency in a wireless device to a received reference frequency, wherein the wireless device operates in at least two frequency bands, the method comprising the steps of:
- determining the frequency band of operation of the wireless device;
- adjusting a loop gain value based on the determined frequency band of operation of the wireless device;
- providing a control voltage to the voltage controlled oscillator based on the determined frequency band of operation of the wireless device so as to provide a frequency adjusted local reference frequency;
- revising the control voltage provided to the voltage controlled oscillator based on an error associated with the frequency adjusted local reference frequency, based on the received reference frequency and based on the adjusted loop gain wherein said step of revising the control voltage is carried out by a subroutine stored in a memory at a location associated with an interrupt vector;
- detecting a change in sign of the error associated with the frequency adjusted local reference frequency;
- and
- revising the location associated with the interrupt vector to a memory location associated with a subroutine utilizing a decreased loop gain if a change in the sign of the error is detected.
A method of synchronizing a voltage controlled oscillator which provides a local reference frequency in a wireless device to a received reference frequency, wherein the wireless device operates in at least two frequency bands, the method comprising the steps of:
- determining the frequency band of operation of the wireless device;
- adjusting a loop gain value based on the determined frequency band of operation of the wireless device;
- providing a control voltage to the voltage controlled oscillator based on the determined frequency band of operation of the wireless device so as to provide a frequency adjusted local reference frequency;
- revising the control voltage provided to the voltage controlled oscillator based on an error associated with the frequency adjusted local reference frequency, based on the received reference frequency and based on the adjusted loop gain;
- and
- increasing the control voltage to provide an initial control voltage greater than the control voltage corresponding to the operating frequency.
A method of temperature compensating a local reference frequency in a wireless device to a received reference frequency, the method comprising the steps of:
- initiating a table of temperature compensation values which compensate the local reference frequency for temperature, wherein the temperature compensation values have associated with them an indicator of accuracy which indicates an accuracy of determination of a corresponding temperature compensation value;
- measuring a temperature of the wireless device;
- adjusting the local reference frequency of the wireless device initially based on one of said temperature compensation values associated with the temperature of the wireless device, and refining the adjustment based on the received reference frequency;
- determining the mean frequency adjustment of the local reference frequency;
- determining a received accuracy indicator associated with the received reference frequency which indicates an accuracy of a source of the received reference frequency;
- comparing the received accuracy indicator with the indicator of accuracy associated with said temperature compensation value associated with the temperature of the wireless device so as to provide a relative accuracy comparison;
- and
- updating the table of temperature compensation values based on the relative accuracy comparison.
A method of accelerating frequency lock in a wireless device when a hand over from a first base station operating at a first frequency to a second base station operating at a second frequency occurs, the method comprising the steps of:
- selecting a high initial loop gain of an automatic frequency control loop associated with a voltage controlled oscillator of the wireless device, wherein the voltage controlled oscillator provides a local reference frequency for the wireless device;
- measuring the frequency error between the local reference frequency generated utilizing the high initial loop gain value and a received reference frequency from the second base station;
- detecting that the measured frequency error has changed sign;
- and
- progressively reducing the loop gain of the automatic frequency control loop responsive to detected changes in sign until a minimum loop gain associated with the second frequency of operation of the second base station is achieved, wherein the minimum loop gain associated with the second frequency of operation is different from the minimum loop gain associated with the first frequency of operation.
A system for synchronizing a voltage controlled oscillator which provides a local reference frequency in a wireless device to a received reference frequency, wherein the wireless device operates in at least two frequency bands, the system comprising:
- means for determining the frequency band of operation of the wireless device;
- means for adjusting a loop gain value based on the determined frequency band of operation of the wireless device;
- means for providing a control voltage to the voltage controlled oscillator based on the determined frequency band of operation of the wireless device so as to provide a frequency adjusted local reference frequency;
- means for revising the control voltage provided to the voltage controlled oscillator based on an error associated with the frequency adjusted local reference frequency, based on the received reference frequency and based on the adjusted loop gain;
- and
- means for compensating the loop gain based on an operating temperature of the wireless device.
A system for synchronizing a voltage controlled oscillator which provides a local reference frequency in a wireless device to a received reference frequency, wherein the wireless device operates in at least two frequency bands, the system comprising:
- means for determining the frequency band of operation of the wireless device;
- means for adjusting a loop gain value based on the determined frequency band of operation of the wireless device;
- means for providing a control voltage to the voltage controlled oscillator based on the determined frequency band of operation of the wireless device so as to provide a frequency adjusted local reference frequency;
- and
- means for revising the control voltage provided to the voltage controlled oscillator based on an error associated with the frequency adjusted local reference frequency, based on the received reference frequency and based on the adjusted loop gain;
- means for detecting a change in sign of the error associated with the frequency adjusted local reference frequency;
- and
- means for decreasing the loop gain value if a change in the sign of the error is detected.
A system for synchronizing a voltage controlled oscillator which provides a local reference frequency in a wireless device to a received reference frequency, wherein the wireless device operates in at least two frequency bands, the system comprising:
- means for determining the frequency band of operation of the wireless device;
- means for adjusting a loop gain value based on the determined frequency band of operation of the wireless device;
- means for providing a control voltage to the voltage controlled oscillator based on the determined frequency band of operation of the wireless device so as to provide a frequency adjusted local reference frequency;
- means for revising the control voltage provided to the voltage controlled oscillator based on an error associated with the frequency adjusted local reference frequency, based on the received reference frequency and based on the adjusted loop gain, wherein said means for revising the control voltage is carried out by a subroutine stored in a memory at a location associated with an interrupt vector;
- means for detecting a change in sign of the error associated with the frequency adjusted local reference frequency;
- and
- means for revising the location associated with the interrupt vector to a memory location associated with a subroutine utilizing a decreased loop gain if a change in the sign of the error is detected.
A system for synchronizing a voltage controlled oscillator which provides a local reference frequency in a wireless device to a received reference frequency, wherein the wireless device operates in at least two frequency bands, the system comprising:
- means for determining the frequency band of operation of the wireless device;
- means for adjusting a loop rain value based on the determined frequency band of operation of the wireless device;
- means for providing a control voltage to the voltage controlled oscillator based on the determined frequency band of operation of the wireless device so as to provide a frequency adjusted local reference frequency;
- and
- means for revising the control voltage provided to the voltage controlled oscillator based on an error associated with the frequency adjusted local reference frequency, based on the received reference frequency and based on the adjusted loop gain;
- and
- means for increasing the control voltage to provide an initial control voltage greater than the control voltage corresponding to the operating frequency.
A system for temperature compensating a local reference frequency in a wireless device to be synchronized to a received reference frequency, the system comprising:
- means for initiating a table of temperature compensation values which compensate the local reference frequency for temperature, wherein the initial temperature compensation values have associated with them an initial indicator of accuracy which indicates an accuracy of determination of a corresponding temperature compensation value;
- means for measuring a temperature of the wireless device;
- means for adjusting the local reference frequency of the wireless device initially based on one of said temperature compensation value associated with the temperature of the wireless device, and for refining the adjustment based on said received reference value;
- means for determining the mean frequency adjustment of the local reference frequency;
- means for determining a received accuracy indicator associated with the received reference frequency which indicates an accuracy of a source of the received reference frequency;
- means for comparing the received accuracy indicator with the indicator of accuracy associated with the temperature compensation value associated with the temperature of the wireless device so as to provide a relative accuracy comparison;
- and
- means for updating the table of temperature compensation values based on the relative accuracy comparison.
A system for accelerating frequency lock in a wireless device when a hand over from a first base station operating at a first frequency to a second base station operating at a second frequency occurs, comprising:
- means for selecting a high initial loop gain of an automatic frequency control loop associated with a voltage controlled oscillator of the wireless device, wherein the voltage controlled oscillator provides a local reference frequency for the wireless device;
- means for measuring the frequency error between the local reference frequency and a received reference frequency from the second base station;
- means for detecting that the measured frequency error has changed sign;
- and
- means for progressively reducing the loop gain of the automatic frequency control loop responsive to detected changes in sign until a minimum loop gain associated with the second frequency of operation of the second base station is achieved, wherein the minimum loop gain associated with the second frequency of operation is different from the minimum loop gain associated with the first frequency of operation.
Dependencies are inferred from the claim text.