Method for adjusting the output frequency of a frequency synthesizer

In a communication device that includes a radio frequency (RF) receiver and a frequency synthesizer that provides a local oscillator frequency, wherein the frequency synthesizer includes a reference oscillator, a reference divider, a phase detector, an output frequency divider, a voltage control oscillator, and a multi-bandwidth filter, a method for adjusting the local oscillator frequency, the method comprising the steps of:

• a) detecting a channel adjustment request, wherein the channel adjustment request indicates a selected frequency;
• b) calculating a difference between the selected frequency and a present frequency to produce a frequency difference;
• c) determining a frequency scaling factor;
• d) calculating a frequency adjustment time based on a proportional relationship between the frequency difference and the frequency scaling factor, wherein the proportional relationship is based on time required to charge or discharge a capacitor of the multi-bandwidth filter to produce an optimum pull-back for the frequency difference;
• e) adjusting bandwidth of the multi-bandwidth filter from a first bandwidth to at least a second bandwidth for a duration of the frequency adjustment time;
• f) adjusting the local oscillator frequency from the present frequency to the selected frequency prior to expiration of the frequency adjustment time;
• and
• g) upon expiration of the frequency adjustment time, adjusting the bandwidth of the multi-bandwidth filter from the second bandwidth to the first bandwidth.

In a communication device that includes a radio frequency (RF) transmitter and a frequency synthesizer that provides a frequency reference, wherein the frequency synthesizer includes a reference oscillator, a reference divider, a phase detector, an output frequency divider, a voltage control oscillator, and a multi-bandwidth filter, a method for adjusting the frequency reference, the method comprising the steps of:

• a) detecting a channel adjustment request, wherein the channel adjustment request indicates a selected frequency;
• b) calculating a difference between the selected frequency and a present frequency to produce a frequency difference;
• c) determining a frequency scaling factor;
• d) calculating a frequency adjustment time based on a proportional relationship between the frequency difference and the frequency scaling factor, wherein the proportional relationship is based on time required to charge or discharge a capacitor of the multi-bandwidth filter to produce an optimum pull-back for the frequency difference;
• e) adjusting bandwidth of the multi-bandwidth filter from a first bandwidth to at least a second bandwidth for a duration of the frequency adjustment time;
• f) adjusting the frequency reference from the present frequency to the selected frequency prior to expiration of the frequency adjustment time;
• and
• g) upon expiration of the frequency adjustment time, adjusting the bandwidth of the multi-bandwidth filter from the second bandwidth to the first bandwidth.

In a frequency synthesizer that includes a reference oscillator, a reference divider, a phase detector, an output frequency divider, a voltage control oscillator, and a multi-bandwidth filter, a method for adjusting output frequency of the frequency synthesizer, the method comprising the steps of:

• a) detecting a frequency adjustment request, wherein the frequency adjustment request indicates a selected frequency;
• b) calculating a difference between the selected frequency and a present frequency to produce a frequency difference;
• c) determining a frequency scaling factor;
• d) calculating a frequency adjustment time based on the frequency difference and the frequency scaling factor, wherein the proportional relationship is based on time required to charge or discharge a capacitor of the multi-bandwidth filter to produce an optimum pull-back for the frequency difference;
• e) adjusting bandwidth of the multi-bandwidth filter from a first bandwidth to at least a second bandwidth for a duration of the frequency adjustment time;
• f) adjusting the output frequency of the frequency synthesizer from the present frequency to the selected frequency prior to expiration of the frequency adjustment time;
• and
• g) upon expiration of the frequency adjustment time, adjusting the bandwidth of the multi-bandwidth filter from the second bandwidth to the first bandwidth.