VCO gain tracking for modulation gain setting calibration

• US 6,834,183 B2
• Filed: 11/04/2002
• Issued: 12/21/2004
• Est. Priority Date: 11/04/2002
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Traylor, Kevin, Black, Gregory, Schwartz, Daniel B
• Primary Examiner(s): Urban, Edward F.
• Assistant Examiner(s): CHOW, CHARLES CHIANG
• Application Number:
  US10/287,382
• Publication Number:
  US 20040087285A1
• Time in Patent Office: 778 Days
• Field of Search: 455/126, 455/113, 455/118, 455/164.1, 455/255, 455/164.2, 455/165.1, 455/147, 455/262, 455/260, 455/264, 455/183.2, 455/185.1, 455/186.1, 455/192.1, 455/575.1, 455/550.1, 455/42, 455/44, 455/180--18, 455/182--18, 331/1.R, 331/17, 331/16, 331/44, 331/23, 331/175, 331/25, 331/177.R, 375/376, 375/373, 327/156, 327/159, 332/128
• US Class Current: 455/182.1
• CPC Class Codes: H01Q 3/267 Phased-array testing or checking devices
• CPC Class Codes: H03C 3/0925 applying frequency modulation at the divider in the feedback loop
• CPC Class Codes: H03C 3/0941 applying frequency modulation at more than one point in the loop
• CPC Class Codes: H03C 3/0975 applying frequency modulation in the phase locked loop at components other than the divider, the voltage controlled oscillator or the reference clock
• CPC Class Codes: H03L 7/1974 for fractional frequency division

Abstract

Voltage controlled oscillator (VCO) gain tracking is used for programming modulation gain settings to minimize modulation distortion in a phase locked loop of a mobile station (10). A synthesizer (20) generates a tuning voltage (Vt) for controlling a frequency of a (VCO) modulated radio frequency signal. A controller (22) outputs a modulation data signal and includes an ADC (72) for receiving the tuning voltage from the synthesizer (20) on a VCO feedback loop (70), a gain control lookup table (LUT) (76) for storing gain setting calibration data for respective mobile station sub-bands, and a gain setting (DAC) (78) for outputting a modulation gain control signal to the synthesizer (20). The modulation gain setting calibration data is calibrated using a one-time or continuous calibration methodlogy during, respectively, a background or normal mode of operation.

Claims

1. A system for calibrating mobile station modulation gain settings, comprising:

a synthesizer including a phase locked loop (PLL), the PLL for outputting a tuning voltage for controlling a frequency of a voltage controlled oscillator (VCO) modulated signal; and

a controller in communication with the PLL for outputting a modulation data signal and including;

an analog to digital converter (ADC) for receiving the tuning voltage fed back from the PLL on a VCO gain tracking feedback loop;

a gain control lookup table for storing calibration data, determined based on the tuning voltage fed back from the PLL on the VCO gain tracking feedback loop, one or more respective mobile station sub-bands; and

a gain setting DAC for outputting a modulation gain control signal to the synthesizer, the modulation gain control signal being derived from the calibration data retrieved from the lookup table based on a mobile station sub-band of operation, the modulation gain control signal depending on a curve estimating methodology to mitigate noise associated with the calibration data.

2. The system of claim 1, wherein the synthesizer comprises a multi-accumulator fract-N synthesizer.

3. The system of claim 1, wherein:

the calibration data and the modulation gain control signal respectively comprise modulation gain setting calibration data and a high port gain control signal; and

the PLL comprises;

a loop filter with a high port DAC for converting the high port gain control signal and the modulation data signal input from the controller to produce a full-scale output voltage that represents a gain-controlled signal to be modulated;

a phase detector for generating an error signal based on the tuning voltage; and

a lowpass filter for filtering the error signal generated by the phase detector and a summer for summing the error signal and the signal to be modulated to produce the tuning voltage.

4. The system of claim 1, wherein the controller is programmed to perform a one-time update of the calibration data stored in the lookup table for the one or more respective mobile station sub-bands during a background mode of operation based on multiple tuning voltages measured on respective channels in contiguous sub-bands.

5. The system of claim 1, wherein the controller is programmed to perform continuous updating of the calibration data stored in the lookup table based on multiple measured tuning voltages, each of which is input thereto from the VCO gain tracking feedback loop, at multiple different locations in a sub-band in use during normal mobile station operation.

6. The system of claim 1, wherein the controller programs the calibration data stored in the lookup table for the one or more respective mobile station sub-bands by using curve estimation for the one or more respective mobile station sub-bands, the curve estimation reducing an effect of noise at an output of the ADC and using one of a polynomial curve fitting and a least squares error function.

7. The system of claim 1, wherein the controller programs the calibration data stored in the lookup table for the one or more respective mobile station sub-bands by using curve estimation for a number of measured tuning voltages, each input from the VCO gain tracking feedback loop, the number of measured tuning voltages being greater than a one plus an order of the curve estimation methodology.

8. The system of claim 1, wherein the gain control lookup table is further for storing the calibration data for the one or more respective mobile station sub-bands within each mobile station band.

9. A mobile station controller for controlling a dual port synthesizer, comprising:

an analog to digital controller (ADC) for receiving a tuning voltage fed back on a voltage controlled oscillator (VCO) gain tracking feedback loop and for converting the tuning voltage to a digital signal;

a lookup table for storing high port gain calibration settings for one or more respective mobile station sub-bands, the high port gain calibration setting being based on the tuning voltage fed back on the VCO gain tracking feedback loop; and

a high port gain setting DAC for outputting a high port gain control signal based on the high port gain calibration settings stored in the lookup table in response to a mobile station sub-band of operation, the high port gain control signal further based on a curve estimating methodolgy to mitigate noise associated with the high port gain calibration settings.

10. The mobile station controller of claim 9, wherein the lookup table is updated during a one-time programming of the high port gain calibration settings for the one or more respective mobile station sub-bands stored therein during a background mode of operation and based on multiple tuning voltages measured on respective channels in contiguous ones of the one or more respective mobile station sub-bands.

11. The mobile station controller of claim 9, wherein the lookup table is updated whenever at least two tuning voltages, each of which is input thereto from the VCO gain tracking feedback loop, are measured at different locations in the mobile station sub-band of operation.

12. The mobile station controller of claim 9, wherein the lookup table is for storing the high port gain calibration settings during a mobile station background mode of operation.

13. The mobile station controller of claim 9, wherein the controller is programmed to update the high port gain calibration settings for the one or more respective mobile station sub-bands by using curve estimation for a number of measured tuning voltages, each of which is input thereto from the VCO gain tracking feedback loop, that is greater than one plus an order of the curve estimating methodology during a mobile station background mode of operation for the one or more respective mobile station sub-bands, the curve estimation using polynomial curve fitting to reduce an effect of noise at an output of the ADC.

14. The mobile station controller claim 9, wherein the controller is programmed to update the high port gain calibration settings for the one or more respective mobile station sub-bands by using curve estimation for a number of measured tuning voltages, each of which is input thereto from the VCO gain tracking feedback loop, that is greater than one plus an order of the curve estimation methodology during a mobile station background mode of operation for the one or more respective mobile station sub-bands, the curve estimation using a least squares estimate between a curve estimation model and the calibration data to reduce an effect of noise at an output of the ADC.

15. A method of calibrating modulation gain settings of a mobile station, comprising:

looking up stored calibration parameters, including at least one of a number of sub-bands and number of channel measurements required for calibration of one or more of the number of sub-bands;

transmitting on the one or more of the number of sub-bands;

measuring fed-back tuning voltages resulting from the transmitting on the one or more of the number of sub-bands; and

storing calibration data calculated based on the measuring of fed-back tuning voltages resulting from the transmitting on the one or more of the number of sub-bands for later use in determining respective modulation gain settings for the one or more of the number of sub-bands, the modulation gain settings further based on a curve estimating methodology to mitigate noise associated with the measuring of the fed-back tuning voltages.

16. The method of claim 15, further comprising disabling an amplified output control of a mobile station transmitter prior to the transmitting on a particular sub-band to enable a mobile station background mode of operation.

17. The method of claim 15, wherein the looking up of stored calibration parameters, including at least one of a number of sub-bands and number of channel measurements required for calibration of one or more of the number of sub-bands, includes looking up a number of contiguous sub-bands per band, and a number of tuning voltage measurements required for calibration of the one or more of the number of sub-bands;

transmitting on channels in each of the number of contiguous sub-bands;

measuring multiple tuning voltages during the transmitting on each of the number of contiguous sub-bands; and

storing the calibration data calculated based on the measuring of multiple tuning voltages during the transmitting on each of the number of sub-bands.

18. The method of claim 15, further comprising calculating the calibration data for the one or more of the number of sub-bands by using curve estimation where a number of the fed-back tuning voltages exceeds two plus an order of a curve fitting polynomial and operates to reduce an effect of noise at an output of the ADC.

19. The method of claim 15, further comprising calculating the calibration data for the one or more of the number of sub-bands by using curve estimation when a number of the fed-back tuning voltages exceeds an order of the curve estimation by more than one, the curve estimation using a least squares estimate between a sum of squares of a difference between data produced by a curve estimation model and the calibration data to reduce an effect of noise at an output of the ADC.

20. A method of continuously updating high port gain calibration settings of a mobile station dual port input synthesizer, comprising:

initiating a background mode of transmitter operation;

measuring respective tuning voltages resulting from the initiating of a background mode of operation during transmitter operation at different locations in a mobile station sub-band of operation, each of which is input from a voltage controlled oscillator (VCO) gain tracking feedback loop;

determining a high port gain calibration setting for the mobile station sub-band of operation based on a calculated polynomial model of tuning voltage versus frequency for the mobile station sub-band of operation, the calculated polynomial model based on a curve estimating methodology to mitigate noise associated with the measuring respective tuning voltages; and

storing the high port gain calibration setting for setting high port gain for the mobile station sub-band of operation.

21. A mobile station transmitter configuration, comprising:

a voltage controlled oscillator (VCO) for generating a carrier signal and for receiving a tuning voltage to control modulation of a radio frequency (RF) signal on the carrier signal;

a transmitter in communication with the VCO for transmitting the RF signal;

a synthesizer for generating the tuning voltage input into the VCO for controlling modulation of the RF signal on the carrier signal; and

a controller including an analog to digital converter (ADC) for receiving the tuning voltage fed back from the synthesizer on a VCO gain tracking feedback loop, a gain control lookup table for storing calibration data for one or more respective mobile station sub-bands, and a digital to analog converter (DAC) for outputting a gain controlled modulation signal, that is based on the calibration data retrieved from the lookup table and based on a curve estimating methodology to mitigate noise associated with the calibration data.

22. The mobile station transmitter configuration of claim 21, wherein the synthesizer comprises a multi-accumulator fract-N synthesizer.

23. The mobile station transmitter configuration of claim 21, wherein the synthesizer comprises:

a loop filter with a multiplying DAC for multiplying the gain controlled modulation signal and the modulation data signal from the controller to produce a full-scale output voltage that represents a signal to be modulated; and

a phase detector for generating an error signal based on the RF signal;

the loop filter also including a lowpass filter for filtering the error signal generated by the phase detector and a summer for summing the error signal and the signal to be modulated to produce the tuning voltage.

24. The mobile station transmitter configuration of claim 23, wherein the synthesizer further comprises:

a divider for dividing the RF signal produced by the VCO for producing a divided RF signal that is input into the phase detector;

a reference oscillator for generating a reference oscillator signal that is also input into the phase detector;

wherein the phase detector is able to generate the error signal based on a phase difference between the divided RF signal and the reference oscillator signal.

25. The mobile station transmitter configuration of claim 21, wherein the controller is programmed to perform a one-time update of the calibration data for the one or more respective mobile station sub-bands.

26. The mobile station transmitter configuration of claim 21, wherein the controller is programmed to perform continuous updating of the calibration data for one of the one or more respective mobile station sub-bands in use whenever multiple tuning voltages, each of which is input thereto from the VCO gain tracking feedback loop, at multiple different locations in the one of the one or more respective mobile station sub-bands in use are measured.

27. The mobile station transmitter configuration of claim 21, wherein the controller is programmed to update the calibration data for the one or more respective mobile station sub-bands by using the curve estimating methodology for a number of tuning voltages, each of which is input thereto from the VCO gain tracking feedback loop, that is greater than an order of polynomial curve fitting model by two or more.

28. The mobile station transmitter configuration of claim 21, wherein the controller is programmed to update the calibration data stored in the lookup table for the one or more respective mobile station sub-bands by using the curve estimation methodology for a number of tuning voltages, each of which is input thereto from the VCO gain tracking feedback loop, the curve estimation methodology using a least squares estimate between a sum of squares of a difference between data produced by a curve estimation model and the calibration data to reduce an effect of noise at an output of the ADC.

29. The mobile station transmitter configuration of claim 21, wherein the gain control lookup table is further for storing calibration data for contiguous mobile station sub-bands.

30. The mobile station transmitter configuration of claim 29, wherein the synthesizer comprises a dual port synthesizer, the calibration data comprises high port gain setting calibration data and the gain control lookup table is for storing calibrated high port gain setting calibration data for the one or more respective mobile station sub-bands.